People with owner or team maintainer permissions can remove team members from a team. This may be necessary if a person no longer needs access to a repository the team grants, or if a person is no longer focused on a team's projects.
Warning: If you remove a person’s access to a private repository, any of their forks of that private repository are deleted. Local clones of the private repository are retained. If a team's access to a private repository is revoked or a team with access to a private repository is deleted, and team members do not have access to the repository through another team, private forks of the repository will be deleted.
In the top right corner of GitHub, click your profile photo, then click Your profile.
On the left side of your profile page, under "Organizations", click the icon for your organization.
Under your organization name, click Teams.
On the Teams tab, click the name of the team.
To the right of the name of the person you want to remove, click > Remove from team.