You can revoke the access of a platform at any time from the Settings > Team and Security > Installed Apps area of your Dashboard.
Note: if the third-party platform is creating Subscriptions for you, we strongly recommend first discussing Subscription migration options with the platform before disconnecting. Disconnecting your account from a third-party platform while there are active Subscriptions can have implications depending on how the Subscription was created.
You may be restricted from revoking platform access if you signed up with a Connect platform that has platform controls for connected accounts. Reach out to the platform to initiate the disconnection process for you.