Board Thread:Support Requests - Getting Technical/@comment-26079784-20190419223050/@comment-9605025-20190419225424

CommunityBuilder is a completely different backend from the "regular" wikis. As such, there is no way to "change" between the two. What you can do is use Special:Contact/general to ask staff if they can get rid of the current one so that you can create a new one using MediaWiki at the same URL.