To remove a member from a team go to the team page, and click on the profile photo of the member you want to remove.
This will display the team profile in a flyout, then you click Remove from team from the action menu.
If the team member have completed checklists and tasks, the checklist will still show that they have completed the checklist or task but their profile photo will have a x-icon on the top right indicating that the person is no longer a member of the team.
