That unit is most likely a rear AC unit. You might want to consider keeping it as you live in the desert. It was probably mounted under a bench or something like that.
I would check to see if it's functional. It's probably tied into your factory front AC and removing it could take all the refrigerant out of the system. Is you front AC working? Just follow the lines from that rear unit. If they go under the body and head to the front then it's definitely tied in. You'll have to cap the system and have it recharged.
But do consider mounting it and using it. I specifically wanted rear AC. I live where it's over 100 for much of the year. I think you do too.
Tim - 2013 EB V10 Agile 4x4 SMB PH Ginger Army All Terrain Mobile HQ