As long as you are the room owner, or yourself an admin of the room, you can remove admin privileges from another member (or yourself).
From the room, tap the ellipses in the top right to bring up the room controls.
Select the room member you'd like to remove admin privileges from (they will have a star to the right of their name), and select Remove Admin.
From the room, click the gear to bring up the room controls.
Click the X to the right of the member you'd like to remove admin privileges from, then click done.