Is there a way for a user to edit/delete a reply that they posted?
All users have Edit, Delete and Reply buttons. But these buttons don't exist if the new topic/post status is unapproved. Also, the Edit and Delete buttons are time limited. You can manage the time limit or remove it all in Dashboard > Forums > Settings > Topics & Posts Tab.
Another important part is the permissions of users. If these permissions are disabled for users Forum Access (usually the "Standard Access") in Dashboard > Forums > Settings > Forum Accesses admin page then they'll not be able to Edit, Delete or Reply:
- Can post reply
- Can reply to own topic
- Can edit own topic
- Can edit own reply
- Can delete own topic
- Can delete own reply
BTW, all these are enabled by default, so forum admins don't have to do this, unless you've made some changes in Usergroup <> Forum Access settings and changed the Standard Access for your default Usergroup.
A good topic to understand how forum Usergroup and Forum Accesses work: https://wpforo.com/community/faq/wordpress-user-roles-wpforo-usergroups-and-forum-accesses/