I think it would be a very good option for contributors to have the option of deleting their own submissions or, at a minimum, being able to do so before being approved.
Just yesterday I sent a clear logo for this game: https://gamesdb.launchbox-app.com/games/images/74258
Immediately I realized that it had a cleaning error, I corrected it and sent an improved version including a text that said that the first version was reject. As you can watch both have been approved and now the wrong one is littering the database.
Something similar happened to me a few days ago with a screenshot from another game.
If I had the option to delete my own contributions, now I could leave everything clean.
Greetings.