Hi,

1. If you want to delete an app made in Studio (custom module):

•          Delete menu: Settings → Technical → User Interface → Menu Items → Find & delete.
•           Delete model (if any): Settings → Technical → Database Structure → Models → Find & delete.
•            Delete views: Settings → Technical → User Interface → Views → Filter by model → Delete.
•            Alternative: Uninstall & reinstall Studio (removes all customizations).

2. If you want to uninstall Studio itself:

​Go to Settings → Apps → (search for  "Studio") → Uninstall.

Hope it helps