There is a limited time to edit and remove posts, after that time expires you can't do that anymore.
Also, should someone reply on the thread during that time, it will skip the time.
Well maybe there isn't even any time.
If someone replies to a post I made as example, I am not able to edit it anymore, even if I post it. However if it gets deleted then I am able to edit and delete it again.
Edit by Lion:
Issue now fixed. Thank you for reporting it.