Follow these steps to disable DP1.2 on the U2414H with NO signal input

Buttons =
Preset, Brightness, Menu, Exit, Power

When you press the Menu button, the buttons then are =
Up arrow, Down arrow, Check OK, Back, Power

* Turn off the monitor
* Unplug all video input cabling from the U2414H
* Turn on the monitor
* Press the Menu button
* Press the Check OK button (3rd from left) and HOLD for 15 seconds
* Then disable DP 1.2

here's the original thread: