ClickAlgo you need to use the composer remove [package] command to uninstall an extension, or run composer update after editing composer.json.
Do not use the "uninstall" button from the admin panel, it deletes the extension data and is only intended for when you plan to permanently remove an extension. The oldest Flarum versions might not have the up to date explanation text as to what that feature does, but it's always worked the same and continues to do so: it deletes all database tables and columns added by the extension. But not the settings/permissions.
When jumping so many versions and also jumping from beta to stable, I would suggest directly jumping to the latest Flarum version.
To avoid having to read and apply the instructions from every single release notes, you can start with a new fresh install, and then edit config.php with your existing database credentials, and copy in any avatars or uploads to the public/storage folders.
Even if you have many extensions, you will likely replace multiple of them with alternate extensions, so creating a fresh install and installing the new extensions will likely be quicker and easier.
If you have extensions that you know are still compatible in your destination version, you can keep them installed and even enabled. As long as you work from a backup, there usually isn't any issue with extensions staying active. It's just a best practice to make troubleshooting easier in case something does go wrong.
