No. You cannot delete admin users, but you can deactivate them so they no longer have access to the system.
1) To deactivate an Admin, go to the Admin Users tab in the left-hand navigation bar
2) Locate the profile you would like to deactivate, then click on thier name
3) Scroll down the page to where it says "active", click on it so it no longer shows green, and then click "Submit" at the bottom of the page.