What about a self-destruct "anon" account ? I personally do not use/like anon accounts, but I see people using it and is quite confusing to "talk" with them not knowing exactly with who you are talking. Some even use anon to impersonate others, giving the false impression that X was posting under anon. Sometimes even different anons are answering each others...

How about they can create a self-destruct account like "anon-xxx", where xxx is a random generated number, but it stays the same for 24h or whatever time the creator want. Then when it reach the set time, will delete all the messages.