Here is the steps to remove unused demos and set only one default demo to use.

1. Open this file app/Providers/AppServiceProvider.php. Remove $theme->setDemo(request()->input('demo', 'demo1'));. Uncomment below code and set the param with your selected demo id.
   copy

   $theme->setDemo('demo2');

2. Remove unused demo layout folders resources/views/layout/demo* and remove doumentation folder resources/views/layout/docs
3. Remove unused assets folders resources/assets/demo*
4. Remove unused demo config folders config/demo*
5. This step is to remove documentation pages config and it is optional. Open this file config/global/pages.php. Remove documentation config.