If you want to cancel orders via Facebook, you have to disable this option both in the UpMenu panel and in the account settings on Facebook.
Uninstalling Facebook Online Ordering
Go to "Facebook app".
Click the trash icon next to the restaurant which you want to uninstall.
Then you will see an information: "Are you sure you want to delete the application? (remember to delete the profile tab also)", if yes choose "Ok".
Facebook online ordering has been removed in the UpMenu panel.
Now you need to delete the profile tab in the Facebook panel. Here you can find how to do this.