Kill all processes besides my program in C#

It doesn't get much easier than

Process self = Process.GetCurrentProcess() ;
foreach( Process p in Process.GetProcesses().Where( p => p.Id != self.Id ) )
{
  p.Kill() ;
}

If you need to worry about your parent process (so you don't kill the command shell that launched your process, the answers to the question "How can I get the PID of the parent process of my application" should guide you.

If you run the application from the solution folder, your process will be easily identifiable in the task manager eg: consoleApplication1.exe

You can get the name of the process by:

var cb = Assembly.GetExecutingAssembly().CodeBase;
var processName = Path.GetFileName(cb);

You will see that in your list of processes in task manager, the name of the process is different if you are debugging and you have "Enable the visual studio hosting process" checked. In this instance the process name would be

consoleApplication1.vshost.exe

You can uncheck this option by right clicking on your project and clicking on "Properties" and then selecting "Debug". You should see a checkbox saying "Enable the visual studio hosting process". Deselect the check box.

Your process name will then be

consoleApplication1.exe

List<string> safeProcs = new List<string>() { "App1", "App2", "App3" };

List<Process> procs = Process.GetProcesses()
    .Where(p => !p.Equals(Process.GetCurrentProcess()) && !safeProcs.Contains(p.ProcessName))
    .ToList();
procs.ForEach(p => p.Kill());

I think you should not use (.exe) in your process name and you must use (using System.Linq;) not to make any error while using (.Any()).

if (Process.GetProcessesByName("YourProcessNameGoesHere").Any())
            {
                
Process MyCurentProcess = Process.GetCurrentProcess();
                foreach (Process process in Process.GetProcessesByName("YourProcessNameGoesHere").Where(process => process.Id != MyCurentProcess.Id))
                {
                    process.Kill();
                }
            }

You can use this procedure:

    private void KillProcess(string _process)
    {
        Process[] procs = Process.GetProcesses();

        foreach (Process proc in procs)
        {
            if (proc.ProcessName == _process)
            {
                proc.Kill();
                proc.WaitForExit();
            }
        }
    }

then:

KillProcess(this.ExecutableName);