Steps to enable tethering on Android 6.0 Marshmallow update
Step 1: Ensure you have the correct OEM drivers installed for your handset on the computer
Step 2: Download and install the necessary ADB drivers (v1.4.2)
Step 3: Enable USB debugging on your Android handset:
Go to Settings > About Device, and tap the build number 7 times or until you see 'You're now a developer' message. Return to Settings > Developer options and use the toggle button to turn on USB debugging. Then tap OK button to accept the warning and continue.
Step 4:Connect your device to PC with original USB cable.
Step 5: Launch a command window on your Windows PC.
Step 6: Access ADB shell and run the following command:
adb shell
Step 6: You can now enable tethering by running the following command:
settings put global tether_dun_required 0
Step 7: Just reboot your device once, and tethering will get enabled