This only applies to the scheduling tab associated with a Schedulista account and not to Facebook's native appointment feature in Messenger. Currently, the native Appointments on Facebook feature cannot be disabled or removed.
You can disable the option for clients to schedule an appointment using Schedulista from your Facebook business page and remove the Schedule Appointment tab with these simple steps.
Note on using the scheduling tab on Facebook
We no longer recommend using a scheduling tab as tabs do not appear on the Facebook mobile app for phones and tablets. We recommend using the "Book Now" button instead.
Removing the Schedule Appointment tab
(1) Sign into Facebook and go to your business page
(2) Click Settings from nav menu at the top of the page
(3) On the Settings page, click Templates and Tabs on the menu on the left
(4) Locate Schedule Appointment under the Tabs list and click Settings
(5) When the settings options open, click Edit Settings
(6) On the Edit Schedulista App Settings dialog, click Remove
(7) Click the Okay button
(8) In the settings options, click the on/off toggle to turn the tab Off
(9) Click Save
(10) Click this link to complete the removal
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