There are 2 options available:
Option 1: Revoke Admin Access
Step 1: Click on the 'Groups' icon.
Step 2: Hover your cursor to the right of the user you wish to demote and click on the three dot User menu.
Step 3: From the dropdown, click 'Remove Admin Access.'
Option 2: Delete the user from your account
Step 1: From the dropdown, click 'Remove from Project.'