As an Administrator, you can revoke/reinstate Team Members and Reviewers to/from Engagements.
There are two places where revoking and reinstating can occur:
From the User Details page (Team Members and Reviewers)
From the Engagement User Management tab (Team Members only)
Revoking a user from an engagement means that they no longer have access to that particular engagement. This does not affect any other engagements that a user may be assigned to.
The User Details page will contain a historical record of all engagements that the user has been assigned to with an indication if they are active or have been revoked.