If you want to disconnect GitHub, go to the settings tab of your application and click on Disconnect GitHub.
Next, you will see a pop-up window ‘Are you sure?’, click on OK and you will disconnect your app from GitHub.
Note: if you made some schema changes and don't want to push them into your generated branch, you can disconnect your main GitHub repository from the Settings tab and then connect a new one and push there your changes.
Important clarification! Be aware of the fact that if you disconnect your current GitHub repository, you will not be able to reconnect it.