To block Pepperi support access to your backoffice go to Setting -> Company Profile and de-select the "Allow Support User" check box.
Deselecting the box will block Pepperi Support from being able to access your account.
To enable Pepperi support access leave the box checked.
The check box has no connection to your mobile devices or user accounts. Pepperi has no access to your your user accounts, and your passwords are encrypted and can't be accessed by anyone.