Remove User Sharing of Contacts via API

One can share a contact with another user with an action set, but there is no way to remove that sharing. We would like to remove a share once someone begins to work the contact so that other sales reps don’t see the lead anymore. Is there a way to accomplish this via API?

The action set says “share with another user”, however, it is actually changing the owner id field on the contact. The owner id can be changed by the api at any time and that should again restrict it to that owner (assuming the original creator of the record).

Well that’s what I would have expected, but I don’t think addresses the problem. The client is looking at this part of the user interface:
and seems to think it is allowing the shared user access to the contact record. Since there are multiple shared users, this can’t just be the owner id. They want to remove access to certain of those shared users. What am I missing?

Unless they have a view that isn’t exposed to the api, the only change is on the owner id so there’s no telling without more to look at.

Contact sharing is a separate feature from the owner id field. Unfortunately its modification is not supported by the API.