Replying to those posts and leaving the communities will not perma-ban you, though! You are welcome to rejoin us if/when you decide to come back. You can rejoin your House or choose to be re-sorted.
You can do all of this at your houses leaving/etc post:
Gryffindor | Hufflepuff | Ravenclaw | Slytherin
Reminder: leaving posts in the main comm will result in 10 points gone and a ban from returning for 6 months.