There are two ways of doing this - you can use Nop's utility, however the built in Atomic one is a little easier, just not as powerful as far as custom queries go. I would start with the built in one first. To access:
Run AtomicManager.exe
Check-mark Advanced Options
Click the Advanced Tab
Click the Game List Tab
Check-mark Use predefined games list
Give it a name if you wish, or leave the default
Click the Game List Tab
First add all the games by clicking the >> Button
You should see all the roms move from the left (Available Roms) to the right (GameList)
In the center, click the drop-down under Categories File
Ignore the categories with + in the beginning
Choose the Mature.ini
Click the drop down under Select category
Choose the *Mature*
Click the Remove category button
And repeat for the other categories.
Mahjong is under Catlist.ini, Tabletop.
You might also want to remove the Quiz ones by foreign language as well.
As far as the non-working, that would be dependant on your version of Mame. Which one are you running? I can build you an ini for that fairly easily, let me know.
Also, when you're all done, make sure to check-mark the Sort option on the bottom, and then click Save, Save, Ok, and Close.
Enjoy!
