In some scenarios, you may need to remove a subscription from a system; you may be upgrading the system which requires a new subscription or trying to free an entitlement for another system.
Open the Subscription Manager user interface:
[root@server ~]# subscription-manager-gui
Select the My Subscriptions tab, and select the subscription you want to remove.
Click Yes to confirm the removal.
After you have removed the subscription from Subscription Manager, verify the subscription entitlement is now free in Red Hat Customer Portal, as well