If the "artist" from Etsy made it himself he would for sure be able to do so himself. So apparantly he didn't make the art. So doesn't sound really legit to me.
But if you provide a psd/ai/pdf of it I am sure someone could help you.
^This -- If he made it then he'd have the photoshop file with the layers so he could hide the MAME text and just add your text -- without that it's much more work since you'd have to patch the background objects back in after removing the text or add other background objects to make it look right since you can't remove the text and leave the background behind it if you don't have the original background image.
If you have the full background image adding the text you want would be fairly easy !
A quick Google image search shows this 1920x1080 copy of the background image that might prove useful :
Pretty sure the rest is just a couple more images that they overlayed for the sides - but that part is what you need to cover up the Mame LOGO if you don't have the full layered pic.