Deletion of messages may well be a moderator privelege. You soft delete it, which tags it for the mods to look at, giving a reason why you want to delete it and they delete it for you. oft delete does make it disappear to anyone but the mods as soon as you click it, though, so it is still more or less deleted.

Its possible this is a default setting of the board that the mods have not bothered to change - in case you were wondering why the mods may want to see what you are deleting