Useful Script for Surface Book 2 to toggle off GTX when attempting to detach the screen.

ToggleGTX.ps1

# Useful script for detaching the screen of Surface Book.
# Run if detach light blinks red indicating that it cannot be detached
# since applications are preventing the detach.
#
# Option 1: Copy-paste into powershell window.
#
# Option 2: Run as PowerShell script (requires execution policy change):
# https://superuser.com/questions/106360/how-to-enable-execution-of-powershell-scripts
#
Try {
	$GtxId = (Get-PnpDevice -FriendlyName "*GTX*").InstanceId
	echo "  DeviceID = $GtxId"

	echo "Disabling GTX."
	Disable-PnpDevice -Confirm:$false -InstanceId $GtxId
	Read-Host -Prompt "Safe to detach. Hit enter to re-enable." 

	echo "Enabling GTX."
	Enable-PnpDevice -Confirm:$false -InstanceId $GtxId
} Catch {
	$ErrorMessage = $_.Exception.Message
	$FailedItem = $_.Exception.ItemName
	echo "Try Run as Admin."
	echo "ERROR: $ErrorMessage"
	echo "ERROR: $FailedItem" 
} Finally {
	Read-Host -Prompt "Press any key to quit" 
}

Thanks! @GleasonK @jonaskuske