Timer actualTimer = new Timer(obj => Console.WriteLine("Timer!"),
    null, 0, 1000);

Timer killingTimer = new Timer(obj =>
{
    Console.WriteLine("Killing timer!");
    // Set the dueTime and timeout to infinite, to stop the timer.
    actualTimer.Change(Timeout.Infinite, Timeout.Infinite);
    killingTimer.Change(Timeout.Infinite, Timeout.Infinite);
}, null, 5000, 5000);

Console.ReadLine();

Timer actualTimer = new Timer();
actualTimer.Interval = 1000;
actualTimer.Elapsed += (sender, e) => Console.WriteLine("Timer!");
actualTimer.Start();

Timer killingTimer = new Timer();
killingTimer.Interval = 5000;
killingTimer.Elapsed += (sender, e) =>
{
    Console.WriteLine("Killing timer!");
    actualTimer.Stop();
    killingTimer.Stop();
};
killingTimer.Start();