From a moderator point of use that has permission to hard delete topics and posts, it's a pain that you can't hard delete topics and posts right away. Instead you can only soft delete them at first (send to trash), and then you have select all the same topics/posts again (a second time) to hard delete them next. There should be an option to bypass soft delete and be able to just hard delete them right away "first time" around when wanting too as admin or moderators with hard delete permission.
No fun selecting 10 posts in a topic to delete spread across 4 pages and then having to go back to those 4 pages and re-select all the same posts again to hard delete.
phpBB does it I use by having a check box you tick to simply hard delete topics first time instead of them being sent to trash as soft deleted.