Disable laptop screen when lid is closed

Solution 1:

Launch Presentation Display Mode with Win + P

Select "Second screen only"
Got to Control Panel > Power Options > Change what closing the lid does

Set 'What happens when lid is closed' to 'Do nothing'

Solution 2:

See below for how I do it. Here is a good ref I used to help me -

Chron - How to Disable a Laptop Monitor to Use a Regular Monitor

My Setup

(1) Laptop (Win10 Home)
(2) LCD Monitors

Need

Output to both displays with laptop closed and laptop-display off

Steps

Open Settings->Display ('Change Display Settings')
Identify which display you'd like to disable (#1 for me)
Select display (tap on #1)
Scroll down to 'Multiple displays', set to 'Disconnect this display' & Confirm

Here is how to confirm, Settings will show greyed out if off -

With Laptop Display Enabled
With Laptop Display Disabled

Solution 3:

This will be sort of an addendum to J-Dizzle's answer I'm making because I couldn't find the 'Disconnect this display' option in the last step.

The only real difference is ensuring your laptop monitor is not your main display before trying to disconnect it. Perhaps this is common sense, but it took me a while to figure out. Big thanks and credit to J-Dizzle for his answer though!