Under User management you can easily edit a guest’s permissions and also change their role.
On the user you want, click on ✏️ Edit on the far right
This will open the Account management - here you can:
Select a new access role for Cockpit and/or Cloud – you can also change the guest role to a different one
Permissions for certain profile groups in Cockpit and/or specific Clouds – turn on or off
Save changes