You are correct the way to cancel to process is to set the Cancel properety to true in of the 2 event handlers. There is no direct way to cancel the task.

Hi Attila Grozli-Nagy, Hendrik Striepe

The following is an example of how you can assign the cancel property to true from an automatic task that is executed via the project automation

public class CancelBatchTaskExample
	{
		private CancellationTokenSource _cancellationToken;

		public void Execute()
		{
			// 1. Get the projects controller
			var projectsController = SdlTradosStudio.Application.GetController<ProjectsController>();

			// 2. Get the current project (if null, get first selected project)
			var currentProject = projectsController.CurrentProject ?? projectsController.SelectedProjects.FirstOrDefault();
			if (currentProject == null)
			{
				return;
			}

			// 3. Get the target language file GUIDs
			var language = currentProject.GetProjectInfo().TargetLanguages.FirstOrDefault();
			var projectFiles = currentProject.GetTargetLanguageFiles(language);
			var guids = projectFiles.Select(projectFile => projectFile.Id).ToArray();

			// 4. create new cancellation token; cancel the previous, if exists
			_cancellationToken?.Cancel();
			_cancellationToken = new CancellationTokenSource();

			// 5. Run a task
			System.Threading.Tasks.Task.Run(delegate
			{
				// demonstration of cancelling the task after 1 second
				_cancellationToken.CancelAfter(TimeSpan.FromSeconds(1));

				return currentProject.RunAutomaticTask(guids, AutomaticTaskTemplateIds.AnalyzeFiles, StatusEventHandler, MessageEventHandler);

			}).ContinueWith(t =>
			{
				Trace.WriteLine(t.Result.Status);
				foreach (var message in t.Result.Messages)
				{
					Trace.WriteLine(message.Message);
				}
			});
		}

		private void MessageEventHandler(object sender, TaskMessageEventArgs e)
		{
			if (_cancellationToken.IsCancellationRequested)
			{
				e.Cancel = true;
			}
		}

		private void StatusEventHandler(object sender, TaskStatusEventArgs e)
		{
			
			if (_cancellationToken.IsCancellationRequested)
			{
				e.Cancel = true;
			}
		}
	}