You will only be able to remove users from your team if your user role is either an Admin or Manager, review our What do the different roles mean? guide for more information on the different roles.
If you have the correct permissions, Click the "Team" link in the top menu. This takes you to the "Team Management" section.
You will be presented with the "Team Overview" page which will show you a list of all the users currently in your team and their role.
From the list, find the person you wish to delete and click the "Manage" button on their row.
You will be taken to a page allowing you to manage that users details. Scroll down to the bottom of the page and there will be a "Delete User" box.
Click the "Delete User" button and then click "OK" to confirm the deletion.