This blog describes the process.
It works for me (screenshots below). The problem is that this will remove only one specific profile fragment from the profile store and a full cleanup of all profile fragments tied to this profile does (to my knowledge) not happen. Maybe someone else has some more info on this one. You could surely also create a delete request (Privacy > Requests > Create Request), but this is not meant to support bulk deletions (and will also take a while to process).
https://platform.adobe.io/data/core/ups/access/entities?schema.name=_xdm.context.profile&entityIdNS=... namespace>&entityId=<your namespace value linked to the profile>



Cheers from Switzerland!