How do I remove the Demo Mode on my 28in UHD LED CrystalPro 4K 60Hz DisplayPort, HDMI/MHL, DVI Monitor (Picture In Picture |Picture By Picture) - Black / Aluminum Bezel?

In order to leave Demo Mode, you would need to press and hold the Select button for about 8-10 seconds.

Pressing the Select button for 8-10 seconds, when not in Demo Mode, will activate Demo Mode.