If you need to change a team member's role from Admin to Assistant or from Assistant to Admin, you can follow these steps:

First, remove or cancel the invitation for the team member whose details you'd like to change. You can do this by following the instructions provided here.

Next, re-invite the team member and select the new role you'd like them to have, either Admin or Assistant. Fill in their details again and wait for them to accept the invitation. You can refer here for guidance on how to invite a new team member.