If you are the room owner or admin of a room, you can make any other user an admin.
From the room, tap the ellipses in the top right to bring up the room controls.
Select the room member you'd like to make admin, then select Make Admin.
To remove an admin, follow the same steps and select Remove Admin.
From the room, click the gear to bring up the room controls.
Select the Member(s) you'd like to make room admin.
Click the Make Administrator button.
To remove an admin, click the X to the right of their name, then click done.