可以通过以下代码来撤销将“Automation status”更新为“Automated”：

1. 打开“Test Plan”视图
2. 选择要撤销更改的测试用例
3. 点击右键，在弹出菜单中选择“历史记录…”
4. 在历史记录中，找到要撤销的更改并选择它
5. 点击“撤销”按钮，然后保存更改

示例代码如下：

using Microsoft.TeamFoundation.TestManagement.Client;

// Connect to the TFS server
TfsTeamProjectCollection tfs = new TfsTeamProjectCollection(new Uri("http://tfsserver:8080/tfs"));
tfs.Authenticate();

// Get the test plan
ITestManagementService tms = tfs.GetService();
ITestManagementTeamProject project = tms.GetTeamProject("project name");
ITestPlan plan = project.TestPlans.Find(1);

// Find the test cases to undo the update for
ITestCaseCollection testCases = plan.RootSuite.AllTestCases;
foreach (ITestCase testCase in testCases)
{
    if (testCase.Title == "Test Case Title")
    {
        // Undo the update
        testCase.Actions.RemoveAt(0);
        testCase.Actions.Add(new Microsoft.TeamFoundation.TestManagement.Client.DesignStep()
        {
            ExpectedResult = "Expected result",
            Description = "Description",
            StepNumber = 1
        });

        // Save the changes
        project.WitBatchSave(testCase.WorkItem);
        break;
    }
}

其中，“Test Case Title”应该替换为要撤销更改的测试用例的标题。