I know there's usually a 'delete' button on the 'edit entry' page, but I've got 3 unfinished pics where the delete button mysteriously vanished. This is confusing me );

The delete button normally disappears after a while so people won't just get rid of their old drawings... or something like that. if you submit them the delete button will reappear for awhile, so just submit and delete.

Alright, Thanks!

The advice you have been given is questionable my friend, and I am an expert in these matters.