Connected service device removal - callback API call?

If a device (for example light bulb) is removed from an connected service, how to inform this event through the callback ? What is the message format ? OR will this only be picked up during subsequent discovery requests at certain intervals ?

Google Action provide a "RequestSYNC for this purpose ". Is there an ST equivalent ?

Still trying to figure this out how to send an event to ST for device removal for a C2C schema based device.

I have a schema based C2C device based this API

ST support points me to this API for device removal:

if I understand well, I should use the Schema Callabak format for the callback API like this:

“headers”: {
“schema”: “st-schema”,
“version”: “1.0”,
“interactionType”: “callback”,
“requestId”: “abc-123-456”
“authentication”: {
“tokenType”: “Bearer”,
“token”: “”
But what should the contents be here for device removal ?