Open “Studio Managers“ page;
https://sitename.com/exec/manager/managers
2. Click by studios which you need https://sitename.com/exec/manager/performerstudios?manager_id=3&manager_name=username;
3. Select other managers for selected studio and click by update button. Or delete studio;
After this, you can delete “username“ manager here: https://sitebame.com/exec/manager/managers