await UserServicePermissionManager.Delete(UserServicePermission);

Task<UserServicePermission>

DELETE
/api/v1/users/{id}/permissions/{permissionId}

const int userId = 2757;
const int serviceId = 2;
const int permissionId = 3;
const int organizationId = 9999;
var userServicePermission = new UserServicePermission
{
 PermissionId = permissionId,
 UserId = userId,
 ServiceId = serviceId,
 OrganizationId = organization2Id
}; 

var userServicePermission = await _userServicePermissionManager.Delete(userServicePermission);