How to remove certain games
1. Shutdown and unplug the unit and lay the unit on its back. If wall mounted, you may be able to work from underneath (be careful!)
2. Remove the 2 screws from the bottom panel and remove the panel
3. Follow this reference photo to find where the "usb drive" is located.
4. Remove that drive from the system computer and insert into your home computer.
5. You should see a folder structure like this. Under the name of the system folder you choose, there will be files. Normally each file is a game.
For example, the nintendo folder is "nes" and each game is aptly named
7. Simply delete the games you don't want (you many want to make a backup first before deleting)
8. Go through each system and remove as you like. Be sure not to delete files like "gamelist.xml" or neogeo.zip as that's a system file.
Some systems like Atari and Arcade are forced to use an 8 character max name so they are a little harder to discern.
For example "Captain American and the Avengers" is in a file named "captavnu.zip"
So you can see there is some abbreviation that needs to be considered. When in doubt, you can open the gamelist.xml file in that same folder and search for the file name and it will have more details: