I never saw such a switch. I have found that we use some Fn+Fkey combo on some laptops but here you claim it's a switch.
To help move your post forward, add the full model number. Please don't tell use the series such as dv6, there's a lot more than the series required here. Or just hit HP.com and share the link to your laptop support/drive page.
When I first setup my HP notebook, I located a hdmi enable switch on the screen that could enable or disable the hdmi function by clicking it. Can someone help me find it again?