If you just want to remove the Device Name for those devices that you aren't using from the main screen, you can erase the text for those unused LCD buttons. On one of my bedroom MX500's, the only devices on my main screen are TV, DVD, and CABLE. I've left the other seven device positions blank.

From the SETUP screen, press EDIT, then press PAGE, then press the LCD key that you want to erase the Device Name from. The first digit should be blinking - if so then it's ready for you to edit that line of text. Press the down arrow on the circular navigation ring and that deletes the first digit, then arrow right to the next digit and arrow down, and repeat this till all the digits are erased, then press the LCD key again to save your changes to the text. Press MAIN to return to the SETUP screen, or press it twice to completely exit the setup menu.

If you want to also erase or change the text on each individual key for that device, skip the PAGE button above and you'll get thrown into the text for the various pre-programmed commands and you can erase each digit the same way as above. Pressing PAGE first just takes you to the Device name, but not pressing it gives you access to the keys within that particular device.