How to unpublish a page and still keep a draft?

When I logged out the URL generated a 404.

Correct.

Why can I see the page when logged in? Is this documented somewhere in the codex?

I think this is something that codex has but some parts are still not written, like this part for draft.
In the case of draft post your permalink will look like this:

?p=2898&preview=true

And it is not available when you are not logged out as you noted — 404 error page is what you will get.

The same error you will get also for the pending review status when you are not logged in, but the permalink will be the same as for the published post if you are logged in.

Related Posts:

  1. I can’t preview post’s change once they are published
  2. Can we have private drafts?
  3. Custom save button shows ‘Are you sure you want to…’ dialog
  4. I need to modify drafts using custom data from database and then publish it
  5. How to show or hide a post based on meta_value selection?
  6. Visual Studio SignTool.exe Not Found
  7. How can I delay the publishing of a page or post?
  8. How can I set a draft page as parent without publishing?
  9. Display a post’s publish date from 2112
  10. Does blocking xmlrpc.php affect pinging update services like pingomatic
  11. WordPress plugin to publish to multiple remote WordPress blogs
  12. How to disable drafts?
  13. WordPress prompt checklist before publish?
  14. Publish post when edit post form submitted with enter/return pressed on keyboard
  15. Check before publishing, if already exist post with current custom field value
  16. How to make scheduled post preview visible to anyone?
  17. Scheduled Posts and wp-cron – Why don’t scheduled posts publish if too old?
  18. Why does publish_{custom-post-type} fire on update?
  19. Show recent published posts
  20. Does WordPress remove draft status automatically?
  21. What Can I Use To Add A Custom Button Between Publish button and Move To Trash?
  22. Is there a way to know if a post has been published through XML-RPC?
  23. get_terms on save_post hook
  24. Save and Publish button not working after installing SSL
  25. Can I set a timer for pages to be published?
  26. What differences are there between a Privately Published post and a Draft post?
  27. How can I create custom button in post.php
  28. Disable “preview changes” button
  29. Where is the WP auto-save draft JavaScript?
  30. How to allow a user to make their post (ad) a draft, and then publish again without needing approval?
  31. WordPress Comments are automatically publishing
  32. save imported posts as drafts
  33. Update post meta on bulk edit / update
  34. How to modify Publish metabox?
  35. Hiding Draft Post In Admin
  36. Can’t schedule post for another time
  37. How to get the Tags on Publish post hook?
  38. publish_post called too early
  39. wp_publish_post to saved draft, permalinks broken
  40. Calling Different Custom Post Timestamps in a table
  41. Get publish post link?
  42. Controlled publishing in WordPress
  43. redirect deleted / drafted pages
  44. Change the text of the publish button to Save
  45. Remove “Save draft” button without using CSS
  46. problem with publish date not always appearing [duplicate]
  47. What is happening to make my Update/Publish button disabled?
  48. WordPress 4.9.8 doesn’t save if content has style=”
  49. I want to print a message in post ” After one month from publish date”
  50. What is the reason for the new_to_publish hook not working?
  51. After I publish a post where does it go
  52. Remove Save Draft & Preview Buttions.. and also Statius: Draft & Visibility: Public
  53. Should you manually ping new WordPress posts?
  54. l accidentally permanently deleted a Draft. There’s any way I can recover it?
  55. Authors should not publish
  56. How to add custom status to quick edit
  57. i am making text changes on my page show in preview not on live site, why? [closed]
  58. Is WordPress “publish” atomic?
  59. How to move post process to background
  60. Set page to draft on plugin deactivation
  61. How does redirect work when publish date changes and date in url changes?
  62. Hook when post is set from published to draft?
  63. My posts are getting to Auto draft when I try to Publish
  64. Gutenberg publish date datepicker
  65. How Google Indexer should only index published pages
  66. Publish and go to page [duplicate]
  67. Publish Post Action Not Working
  68. Is it normal for a scheduled post to say “Missed Schedule”
  69. Manage multiple wordpress installs (Best Practice)
  70. Users can only save their draft once before saving for revision
  71. Showing the next post’s title, even if it’s an unpublished post
  72. Force Publish Future (Scheduled) Posts Immediately [duplicate]
  73. Can’t publish posts, Jetpack won’t connect, empty notification emails to my inbox [closed]
  74. Remove “minor-publishing” div from Publish admin metabox
  75. Edit the Publish Widget Options
  76. Default pages to be unpublished – possible?
  77. Return All Post from publish to draft [duplicate]
  78. Duplicate post on publish
  79. How is it possible to use a very reduced version of WordPress?
  80. Problems in updating a self-developed plugin
  81. when I Try to Create new Post or Page it goes Draft(I can’t post Anything)
  82. How to handle security on a wordpress site? [closed]
  83. Include user defined styles without including wp-load
  84. Automatically Updating Publish Date Bug
  85. A question on creating filters for custom posts using taxonomy
  86. I want to allow the use of a data-flw attribute in links in comments
  87. Best practice – pages – ACF or inline coding
  88. wpdb custom tables without plugin
  89. Check if CTP category taxonomy is set in shortcode
  90. Reusing header.php from Yii application
  91. Extract Information from post content (using regex?)
  92. Customise Grouped Product display in Woocommerce with custom column
  93. Page flickers in customization mode
  94. When is the wp-settings-[time] cookie generated?
  95. Extend WordPress Audio Widget to accept HLS (.m3u8) URLs
  96. Dev and prod on the same database- dev version active for IOS
  97. Flexslider empty slide
  98. Custom Form Input not saving to Database
  99. One Post with different content, depending on a Page
  100. How to show only the date, the title and a little “summary” of my WordPress post in my custom theme?