MobileNotifications.RemoveDeliveredNotifications
From Xojo Documentation
Method
MobileNotifications.RemoveDeliveredNotifications(identifiers() As String)
New in 2020r2
Supported for all project types and targets.
New in 2020r2
Supported for all project types and targets.
Removes the specified notifications that have already been delivered.
Notes
You may wish to remove delivered notifications if no longer wish the user to see the notification in the iOS Notification Center.