When you cancel your subscription, while Reserve with Facebook or Reserve with Instagram is still active, the reserve button will still appear on your Facebook or Instagram Page.

To disable it, you will need to go to the Facebook Page, on which you wish to deactivate the button.  

To disconnect your connection:  

1. Click on your profile picture in the top right of Facebook. 
2. Select Meta Business Suite.
3. Select Settings.
4. Select Integrations.
5. Click Connected Apps.
6. Select Mozrest.
7. Click Remove App.

That is it! This will remove your connection for both, Facebook and Instagram.