I am aware there is a feature request for this functionality but at this moment this is not possible from UI or API.

Hi @aliraj , is there a public list where we can find that feature request? I'm just trying to reference that to avoid raising this request.

These are the links that was shared to achieve this via API.

API to close alerts in SIEM: https://cloud.google.com/chronicle/docs/reference/rest/v1alpha/projects.locations.instances.legacy/legacyUpdateAlert#LegacyFeedback

You will need the Alert IDs as input to that, so you would need this endpoint for this purpose: https://cloud.google.com/chronicle/docs/reference/rest/v1alpha/projects.locations.instances.legacy/legacySearchDetections

Unfortunately, I don't have the capability to create a python script to achieve this. 

I think you'll need to ask customer support to add you to the existing internal feature request for this - I'm not aware of any public list.

Unfortunately, I don't have the capability to create a python script to achieve this. 

I've got you, @ev13!  I published this blog post today that describes usage for new python scripts to bulk close alerts: Bulk closing alerts with Python and the Google Security Operations API