Removing or editing a User in your Teams account is done by locating the User in the "All Users" column and then selecting the dropdown menu beside their name:
You can view their license usage, make them an Admin of the Team, remove Admin privileges and, of course, remove them from the Team entirely.
Note: The Team's Account owner cannot be removed from the Team.
A User can also tell if they are an Admin of the Team by looking at their Account details at the bottom of their MyMaxon account page. This section shows what, if any, accounts you are a member of. If you are an Admin of the account the icon will have a small user with a cog wheel on it.
Note: A Teams member can be made an Admin even if the Teams Account is not their own.