The documentation for Office 365 unified API (beta) does not mention how to remove a user from a group once you add them. There is code to unsubscribe (not the same as removing), but it's only for the currently logged-in user.
I tried getting the user ID and issuing a DELETE (using /groups/xxxxxxxxx/members/yyyyyyyyyy), but it does not allow this. I can't even find the record ID that would correspond to a member (rather than a user).
How do I remove a user from a group using the API?