Revoke a role via the REST API interface (IDM 4.7.3)

I have written a simple app that allows me ADD an IDM role to a user using the IDM4.7.3 REST API.  However, I can not find any method/endpoint in the documentation that allows me to REVOKE a user role.  There is an endpoint that revokes a resource but not a role.  I have even checked the 4.8 API documentation and there is no role revoke endpoint there, either.  Am I missing something?  Or is this a glaring omission from the REST API's capabilities?