Update Uninstall_Sysmon64.ps1 (#27)

Check if Sysmon is installed, run the uninstall command with elevated privileges, and handle potential errors. 
Remove the Sysmon executable if the uninstallation is successful.

Chapter 2 Files/SCCM Deployment/Uninstall_Sysmon64.ps1

@@ -1,5 +1,16 @@
-## Sysinternals Sysmon64.exe Uninstaller
-# Perform automated uninstall
-& C:\Windows\Sysmon64.exe -u
-# House keep remaining file
-Remove-Item C:\Windows\Sysmon64.exe
+## Sysinternals Sysmon64.exe Uninstaller
+# Check if Sysmon is installed
+if (Test-Path "C:\Windows\Sysmon64.exe") {
+    try {
+        # Perform automated uninstall with elevated privileges
+        Start-Process "C:\Windows\Sysmon64.exe" -ArgumentList "-u" -Verb RunAs -Wait
+
+        # Housekeep remaining file
+        Remove-Item "C:\Windows\Sysmon64.exe" -Force
+        Write-Output "Sysmon uninstalled and removed successfully."
+    } catch {
+        Write-Error "Error occurred during Sysmon uninstallation: $_"
+    }
+} else {
+    Write-Warning "Sysmon is not installed."
+}