meihuak short answer is yes, if an extension is behaving badly you can can simply disable it until the problem gets fixed by the developer.
And here's a longer answer if you want more details:
If the admin panel is broken an extension can be disabled by editing the database. Most extensions should gracefully fall back when disabled (for example, private discussions become invisible if you disable FoF Byobu, or polls are hidden if you disable FoF Polls) but there are a few extensions that could leak their data when disabled (for example, the See Past First Post extension) so you have to keep that in mind on a production forum.
There are a handful of extensions that can still have an effect on Flarum while disabled, in that case they can be uninstalled temporarily. It happens with some extensions that override entire Flarum files instead of using the official, safer, extension API.
The Flarum extension API is very stable. If you look through the community extensions you'll notice most extensions never required any change since Flarum 1.0 and still work on the latest version. Many got updates but it was to add new features, not fix Flarum compatibility.
We're always happy to help forum owners and developers here on the community should any help be necessary after a Flarum update.
