Tenant is expired, How to uninstall the Clients from Endpoints.
When tenant is expired, Administrators won’t get access to Capture Client Console. So, one can’t trigger uninstallation of the clients from the Console.
Guidance:
In case of expired Tenants
1. Capture Client should be uninstalled from Control panel of the endpoint.
2. Reach out to Support team and get the uninstallation codes for CC
3. Go to "Programs and features" or "Control Panel" on the Endpoint and uninstall the Capture Client. 
4. When prompted, enter the uninstallation code for that specific endpoint received from the Support team

Please refer to "Method 2" in this KB article for more details.
5. If the S1 agent still remains, reboot the machine and then uninstall S1 Agent from "Programs and features" or "Control Panel"