Dash Bezel filler plate
 

Does anybody know if a blank plate is available to delete the 12volt accessory plug with the little mini garage door on the dash? I am looking to roll my own plug and maybe add some switches.

As far as I know ALL Super Duty had that power port regardless of trim level so there would be no factory cover plate. And almost universally people want to add more power ports instead of removing them. There are some USB plugs to use in that power port and combination plugs that have 1/8" headphone style input jack & USB or various other things you can use the power port for.
Or if you are handy with a Dremel and fiberglass you can make it whatever you want.

I've replaced that 12v socket with a dual-USB charger. I installed it without the silicone flip-up cover and left the garage door intact.

Very happy with it, and there's room for a couple rocker switches next to it on that bezel

Here's the link to the one I installed. No idea why adsense put the walmart link in.

I did this exact thing today. Super easy, took about 20 mins. One thing to note, make sure you get the "Non Illuminated" as the power points are 12v hot all the time. The illuminated ones will drain your battery over time.

Not sure why the link that I specifically pointed to the Amazon item redirected to walmart, but I fixed it.