You must be an admin to remove another admin from the organization.
To remove someone as an admin from your organization:
Click on your organization on the left-side navigation
Make sure that you’re an admin by scrolling down to your name and confirming that it says you’re an admin
Scroll to the person you want to add as an admin
Use the drop-down next to their name to select Member. This will remove admin controls from their account for this organization.