Are we still deleting sandbox posts?

The Sandbox currently says:

When you think your challenge is ready for the public, go ahead and post it, and replace the post here with a link to the challenge and delete the sandbox post.

(Emphasis original.)

These days, however, I see a lot of sandbox posts which are edited down to a link but are not deleted. I asked about it in chat and got a couple of responses but nothing definitive. Should we delete sandbox posts after posting them to main? Or should we remove that clause from the Sandbox instructions?

Yes

It's fine to leave them around for a little while, but deleting them is convenient for a few reasons:

1. It makes the number of answers (for non-10k users) more accurately reflect the number of drafts
2. It hides old, posted answers for non-10k users, and with recent changes, 10k users too (by moving them to the bottom)
3. It more clearly visually indicates an answer has already been posted. The H1-paragraph-link formatting is a bit monotonous, and the red background clearly distinguishes old stubs from things that need feedback
4. It prevents them from showing up in searches, making it easier to find drafts which actually need review (by searching, e.g., created:2022 inquestion:2140 king-of-the-hill)

Deleting answers is inconvenient for a few reasons:

1. Deleted answers, their histories and their comments are not viewable to users of all reputation levels. Users below 10k should be able to see this history.

2. Deleted answers are much more difficult to search for than undeleted answers. (e.g. if I want to figure out if a particular challenge was sandboxed). You have to manually wade through the pages of the sandbox. And if you blank them they can easily be filtered out of search results when you are not looking for them.

Leaving answers undeleted makes the sandbox more accessible to all users with the downside that there is some extra fluff hanging around. For this reason I choose to simply blank my sandbox posts when I'm done with them.

Its also worth mentioning that a deleted answer does take up more space than an equivalent undeleted answer, for users that can see them. To make an answer take up as little space as possible the optimal strategy is to blank the entire thing but not delete it. This is no longer much of a concern now that deleted answers are sorted to the bottom so they don't take up real estate, but it does justify why a lot of answers predating this change may not have been deleted.

I think deleting sandbox posts is unnecessary.

I recently deleted a sandbox post whose question was confusing. The deleted post came to the top of the list (for me only) after deleting it. When people make a lot of questions and sandbox posts, and then delete the posts, the deleted posts could really clutter their sandbox up.

Plus, it would probably be unknown as to whether a question was actually posted on sandbox at all, so that using Sandbox can be recommended for the future (especially from new users, that issue is discussed How can we get new users to use the sandbox properly?), although I think this line of argument is weak.