The settings gear at the top right
Deleting an active user
Account admins and program admins can delete users within any program that they have access to. Once deleted, users will no longer be able to log in to Message.
After clicking the gear, click Settings and then User Management. Scroll to find the user that you would like to delete. To the right of their email address, click the red X. Click Revoke access to confirm that you would like to delete the user.
Deleting a pending user
If you would like to delete a pending user (or cancel the invitation for a user who has yet to log in), scroll down to Pending Invitations.
To delete a pending user, click cancel to the right of their email address.