Problem

Currently it is not feasible to use REST API to delete groups within Confluence

Suggested Solution

Request to expose REST API to perform this function.

Why This Is Important

This is essential to control some aspects of group creation/deletion or permissions modification.

Workaround

There is already a request requesting REST API to change permissions : https://jira.atlassian.com/browse/CONFSERVER-44329
There are also external plugins that offer this functionality : https://marketplace.atlassian.com/apps/1217507/rest-api-extender-for-confluence?hosting=server&tab=overview