To disconnect a dapp from your wallet, go to the Settings menu by clicking the Profile Icon in the upper right corner to open the sidebar, and then clicking Settings.
From the settings menu, select Connected Apps. From here, you can see apps you have connected, and disconnect apps you want to disconnect.
Note that disconnecting an app does not revoke its allowances. If you have granted it allowances, you can revoke those allowances using tools like Etherscan's Token Approval Checker.
GameStop cannot make any guarantees regarding the services provided by third party dapps.