Customer issue:

Currently, you can only update heartbeats with a PATCH method, which only adds additional data but does not allow for removing or overriding any data, which means customers can not perform actions such as removing tags via the API.

https://docs.opsgenie.com/docs/heartbeat-api#update-heartbeat-request-partial

Suggested solution:

Add a 'PUT' option to update heartbeats that perform a full override of the existing data. 

Workaround:

Deleting the heartbeat and adding a new one