A Custom App connection can be removed in the same way as any other app connection. Simply visit the Manage Apps listing from the sidebar. Find your Custom App in the list of connected apps and navigate into the connection.
From here, you can choose to Suspend or Remove the app connection.
Suspending or removing the Custom App connection
Deleting a Custom App
To permanently remove a Custom App, including severing any connections that may be linked to it, you can visit Custom Apps from the Apps menu in the sidebar.
Find your Custom App in the list and navigate into it.
From the action menu in the shoulder, choose Remove App.
The Remove App menu item from the action menu
You will be prompted to confirm you wish to remove the Custom App. If there are any existing connections established to the app, you will be provided some information to warn you.
Confirm you wish to remove the app