Simple script which will self destruct after executing.

SelfDestructor.cs

using System;
using System.IO;
using System.Diagnostics;
using System.Reflection;

namespace SelfDestruct {
    public class SelfDestructor {
        const string batScript = "@echo off\r\n" + 
            ":trydelete\r\n" +
            "echo \"%~f1\">\"%~f1\"\r\n" +
            "del \"%~f1\"\r\n" +
            "@timeout /t 0\r\n" +
            "if exist \"%~f1\" goto trydelete\r\n" +
            "attrib -h \"%~f0\"\r\n" +
            "del \"%~f0\"";

        static Process batProcess;
        static FileInfo tempFile;
        static FileSystemWatcher tempFileWatcher;
        static bool isRecreatingTempFile, isSpawningProcess, adminPermission;

        public static void SelfDestruct(bool adminPermission = false) {
            if((batProcess != null && !batProcess.HasExited) || isSpawningProcess)
                return;
            CreateBatchFile();
            SelfDestructor.adminPermission = adminPermission;
            SpawnProcess();
        }

        private static void CreateBatchFile() {
            bool recreateState = isRecreatingTempFile;
            isRecreatingTempFile = true;
            if(tempFile != null)
                try {
                    if(tempFile.Exists) tempFile.Delete();
                } catch { }
            tempFile = new FileInfo(Path.GetTempFileName());
            using(var stream = tempFile.OpenWrite())
            using(var writer = new StreamWriter(stream))
                writer.Write(batScript);
            
            if(!tempFile.Name.EndsWith(".bat", StringComparison.OrdinalIgnoreCase))
                tempFile.MoveTo(tempFile.Name + ".bat");
            
            tempFile.Attributes |= FileAttributes.Hidden | FileAttributes.Temporary;

            isRecreatingTempFile = recreateState;

            RegisterWatcher();
        }

        private static void RegisterWatcher() {
            if(tempFile == null) CreateBatchFile();
            if(tempFileWatcher != null) {
                tempFileWatcher.Filter = tempFile.Name;
                tempFileWatcher.Path = tempFile.DirectoryName;
                return;
            }
            tempFileWatcher = new FileSystemWatcher(tempFile.DirectoryName, tempFile.Name) {
                NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName | NotifyFilters.Size
            };
            tempFileWatcher.Changed += OnChnagedFile;
            tempFileWatcher.Renamed += OnChnagedFile;
            tempFileWatcher.Deleted += OnChnagedFile;
            tempFileWatcher.EnableRaisingEvents = true;
        }

        private static void SpawnProcess() {
            isSpawningProcess = true;
            if(batProcess != null && !batProcess.HasExited) {
                batProcess.Exited -= OnDeleterExited;
                batProcess.Kill();
            }

            batProcess = new Process();
            batProcess.EnableRaisingEvents = true;
            batProcess.Exited += OnDeleterExited;

            ProcessStartInfo startInfo = batProcess.StartInfo;
            startInfo.FileName = "cmd.exe";
            startInfo.Arguments = string.Format("/c \"\"{0}\" \"{1}\"\"", tempFile.FullName, Assembly.GetExecutingAssembly().Location);
            startInfo.CreateNoWindow = true;
            startInfo.UseShellExecute = false;
            startInfo.WindowStyle = ProcessWindowStyle.Hidden;
            startInfo.Verb = adminPermission ? "runas" : "";

            batProcess.Start();
            batProcess.PriorityClass = ProcessPriorityClass.Idle;
            isSpawningProcess = false;
        }

        private static void OnDeleterExited(object sender, EventArgs e) {
            if(!isSpawningProcess && batProcess.HasExited)
                SpawnProcess();
        }

        private static void OnChnagedFile(object sender, FileSystemEventArgs e) {
            if(isRecreatingTempFile) return;
            if(tempFile == null || e.Name == tempFile.Name) {
                bool hasChanged = tempFile == null || !tempFile.Exists;
                if(!hasChanged)
                    try {
                        if(tempFile.Length == batScript.Length)
                            using(var reader = tempFile.OpenText())
                                hasChanged = !string.Equals(reader.ReadToEnd(), batScript, StringComparison.OrdinalIgnoreCase);
                        else
                            hasChanged = true;
                    } catch {
                        hasChanged = true;
                    }
                isRecreatingTempFile = true;
                if(hasChanged) CreateBatchFile();
            }
            if(batProcess == null || batProcess.StartInfo.Arguments.IndexOf(tempFile.FullName, StringComparison.OrdinalIgnoreCase) < 0)
                SpawnProcess();
            isRecreatingTempFile = false;
        }
    }
}

Demostration