Delete invigilators from schedule

["userexternalidexample1,userexternalidexample1"]

{
    "Content": {
        "SuccessfullyRemoved": [
            "13081986"
        ],
        "Errors": []
    },
    "Success": true,
    "Errors": null
}

{
    "Content": {
        "SuccessfullyRemoved": [],
        "Errors": [
            {
                "UserExtId": "89999",
                "Code": 319,
                "Error": "User has not been added as invigilator of this schedule"
            }
        ]
    },
    "Success": true,
    "Errors": null
}