Disable title block on edit screen for a custom post type

I initially didn’t believe this is possible officially at the moment, the post title is always included:

https://github.com/WordPress/gutenberg/blob/a6a0d3d47d24b83a58db7130fa82133428067326/packages/edit-post/src/components/visual-editor/index.js#L77

                        <div className="edit-post-visual-editor__post-title-wrapper">
                            <PostTitle />
                        </div>

The only exception at the moment is if a block template is being edited. In particular, this isn’t a block. There is a post title block but it’s only used in full site editing, not posts.

However, looking at the PostTitle component, it wraps its internal components in a check:

<PostTypeSupportCheck supportKeys="title">

So the reason your post has a title box, is because your post type supports titles.