Disable-BluetoothMDM.ps1

<#
    This script allows modification of local MDM policies.
    It is based on Microsoft Documentation: https://docs.microsoft.com/en-us/windows/client-management/mdm/using-powershell-scripting-with-the-wmi-bridge-provider
    Author: Cornelius Schuchardt, SoftEd Systems GmbH
    
    Must be executed using SYSTEM account.
#>

$namespaceName = "root\cimv2\mdm\dmmap"
$className = "MDM_Policy_Config01_Connectivity02"
$instance = "Connectivity"
$property = "AllowBluetooth"
$value = 0

# Enumerate all instances available for classname
$obj = Get-CimInstance -Namespace $namespaceName -ClassName $className
if (-not ($obj)) {
    New-CimInstance -Namespace $namespaceName -ClassName $className -Property @{ParentID="./Vendor/MSFT/Policy/Config";InstanceID=$instance;$property=0}
}
else {
    $currentValue = $obj.$property
    if ($currentValue -eq $value) {
        Write-Verbose "MDM setting is in consistent state: $property is $value"
    }
    else {
        Write-Verbose "MDM setting must be changed: $property is $currentValue; Should be $value"
        $obj.$property=$value
        Set-CimInstance -CimInstance $obj
    }
}

Very useful script. It seems to only work on Windows 10. Do you know how to do the same thing on Windows 7 & 8? Thanks!

Windows 7 will require a complete different approach as the MDM Providers do not exist. For Windows 8, there is probably another Configuration Service Provider. You could dig in using WMI Explorer and search for Bluetooth on a test device in the relevant namespace (root\cimv2\mdm\dmmap).