synapse/docs/admin_api/delete_group.md

Delete a local group

This API lets a server admin delete a local group. Doing so will kick all users out of the group so that their clients will correctly handle the group being deleted.

The API is:

POST /_synapse/admin/v1/delete_group/<group_id>

To use it, you will need to authenticate by providing an access_token for a server admin: see Admin API.