# Check if the Rapid7 Insight Agent is installed
$agentInstalled = Get-WmiObject -Class Win32_Product | Where-Object { $_.Name -eq "Rapid7 Insight Agent" }

if ($agentInstalled) {
    Write-Output "Rapid7 Insight Agent found. Uninstalling..."

    # Uninstall the Rapid7 Insight Agent
    $uninstallResult = msiexec.exe /x $($agentInstalled.IdentifyingNumber) /qn

    if ($uninstallResult -eq 0) {
        Write-Output "Rapid7 Insight Agent has been successfully uninstalled."
    } else {
        Write-Output "Failed to uninstall Rapid7 Insight Agent. Exit code: $($uninstallResult)"
    }
} else {
    Write-Output "Rapid7 Insight Agent is not installed on this system."
}
 

Hey @anuj.johri that is happening because you are trying to query a 64-bit registry key using a 32-bit powershell process. The code below will 

# ScriptBlock to Find Software
$scriptblock = {
$softwareName = "Rapid7 Insight Agent"
$uninstallKey = "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall"
Get-ChildItem $uninstallKey | Get-ItemProperty | Where-Object { $_.DisplayName -match $softwareName}
}

# Query Software
$softwareKey = @(& "$env:SystemRoot\sysnative\WindowsPowerShell\v1.0\powershell.exe" -ExecutionPolicy Bypass -WindowStyle Hidden -NoProfile -NonInteractive -Command $scriptBlock)

IF($softwareKey)
{
  # Get Uninstall String
  $uninstallString = $softwareKey.UninstallString
  $uninstallString = $uninstallString.Replace("MsiExec.exe /I","/X ")
  $uninstallString = $uninstallString.Replace("MsiExec.exe /X","/X ")

  # Run Uninstall
  Start-Process -FilePath MsiExec.exe -ArgumentList "$uninstallString /qn" -Wait

  # Validate
  remove-variable softwareKey
  $softwareKey = @(& "$env:SystemRoot\sysnative\WindowsPowerShell\v1.0\powershell.exe" -ExecutionPolicy Bypass -WindowStyle Hidden -NoProfile -NonInteractive -Command $scriptBlock)
  IF($softwareKey)
  {
    Write-Output "Failed to remove with: MsiExec.exe $uninstallString /qn"
  }
  else
  {
    Write-Output "Rapid7 Removed Successfully"
  }
}