Removes one of the caller's reactions from the email. Returns the updated record.

The record is looked up within the caller's tenant, and the caller must also be allowed to access the entity the email is linked to (employer, customer, lead, workflow or meeting, checked in that order); otherwise that entity's access check rejects the request. The caller also needs the update permission of the linked entity type (employers:write, leads:update, workflows:update, customers:update or meetings:update), checked in the service layer.

Errors: 403 if the reaction belongs to another user or the update permission is missing; 404 if the record or the reaction does not exist.