For SSH user management, navigate to the 'Access' tab at the environment level. You can check or uncheck the 'Allow SSH' box for each user you wish to grant or remove access to. You must also add the users SSH public key. If a user does not have a SSH key, users can add one under their user 'Settings'.
Granting a user SUDO permissions gives the user ALL rights on your server.
Note: if a timeout error occurs, verify your server status. Your disk may be full or there may be a process running. You can check the 'Server' tab for further details.
If the system asks for your password, your public key or user name may not be correct, or, the update on your server has not yet finished.