UnInstall Module
Go to your admin panel and select Module Manager >> Modules

Go to the Module Manager and click the "Uninstall" button next to the module you want to remove.

To clean up Update or Dump Autoload composer
Composer update. Go to your project root dir cd /path/to/project_root/ using SSH and run composer update

Some hosting disabled composer update. Contact hosting support and enable it. You may run composer dump-autoload if composer update unavailable.
