There are 5 options
1) Ask The Client
You haven’t been given what you need to do your work, so you should request it rather than hacking in to the clients site. This would be the Professional and ethical thing to do
2) Reset Password link
Using the standard password reset link should do the job
3) WP CLI
You can use WP CLI to set the password, or add a new administrator user.
e.g. to update the user with ID 22:
wp user update 22 --password="newpass"
4) Via The Database
Passwords are salted, but you can replace them with an MD5 hash. The caveat being that as soon as that hash is checked, if it matches the password, then it gets replaced with a salted version at:
https://core.trac.wordpress.org/browser/tags/4.9.8/src/wp-includes/pluggable.php#L2236
5) emergency.php
If all other options fail, there is emergency.php
. The file is dangerous, and should be removed once used, but it will allow you to reset the password of an admin user
- Save the script below as a file called emergency.php to the root of your WordPress installation (the same directory that contains
wp-config.php).- In your browser, open http://example.com/emergency.php.
- As instructed, enter the administrator username (usually admin) and the new password, then click Update Options. A message is displayed
noting the changed password. An email is sent to the blog
administrator with the changed password information.- Delete emergency.php from your server when you are done. Do not leave it on your server as someone else could use it to change your
password.
But the best avenue would be to ask the client or your employer for access, it’s not an unreasonable request, and it’s unreasonable to ask you to break into the site in order to do work.