SPSubburaj Pandian Veluchamy Syncfusion Team July 27, 2017 06:16 PM UTC
Thank you for contacting Syncfusion support.
Currently we are checking on this requirement to achieve in sample level, we will analyze and update you the details at the earliest. We appreciate your patience until then.
Subburaj Pandian V.
VRVigneshkumar Ramasamy Syncfusion Team July 28, 2017 09:56 AM UTC
Thanks for your patience.
As of now we don’t have any direct support to prevent deleting appointment when Delete key pressed. But we have created a sample level workaround to achieve your requirement by using AppointmentCollectionChanged event. Please find the sample in the below link.