If you wish to stop using StructuredDiscussions on your wiki, the recommended approach is to convert the StructuredDiscussions boards to text with convertToText.php, delete all StructuredDiscussions boards, change settings to prevent use of StructuredDiscussions, and leave StructuredDiscussions installed.
It is not recommended to uninstall StructuredDiscussions when there is existing content. Doing so will have the following effects:
- Valid log entries don't render, so you just get "flow-delete-post (Test)", instead of something like "deleted a post on "Test" on Structured Discussions/Sandbox (delete test post)" (these are different examples, but the same action type; correct version also has proper links): https://en.wikipedia.org/w/index.php?title=Special%3ALog&type=delete&user=Fram&page=&year=2016&month=9&tagfilter=&subtype=
- The namespace stops existing, which still causes breakage even with wikitech:Flow. See https://en.wikipedia.org/w/index.php?title=Special%3ALog&type=&user=Roan+Kattouw+%28WMF%29&page=&year=2016&month=-1&tagfilter=&hide_thanks_log=1&hide_patrol_log=1&hide_tag_log=1&hide_review_log=1 (namespace is missing even for the workaround deletes).
- Special:Undelete will throw an MWUnknownContentModelException when someone attempts to preview a deleted StructuredDiscussions board.
If you still uninstall StructuredDiscussions, you should follow the steps at wikitech:Flow to avoid additional problems.