Changing own admin rights result in 404

Created by: Razer6

After b01f8b63 deleting own user is not possible anymore but changing own access rights still possible. Removing administrator rights from system result in 404 when saving profile.

Steps to reproduce:

1. Login as admin and edit own profile
2. Remove Administrator rights and save profile
3. 404

Expected results

Same as deleting the own user, it should not be able to remove own admin rights

Logs

All green

Running on 5.3.0 148eade9