Zend certified PHP/Magento developer

Dell laptop with one HDMI. I added an HDMI adapter to connect three monitors. But cannot extend display to each without the laptop

I want to shut off the laptop so I can extend the 3 monitors and have it work so my mouse can go from one to the other and NOT through the laptop. I am not using the screen on the laptop and it is behind the monitors. Lid down but it still shows as one of the monitors on the display. So the mouse goes from one laptop to the other. I cannot seem to get it to use only the three and yet still run.
I saw some instructions to go through the Device Manager and that did not work. I also saw an option to go through Power and find the shut-off laptop display and work with the lid down. I do not have that as an option.
Help. This is my work computer and I need it as I am working from home.