Use RomLister in Batch file mode using "del %rom%.zip" instead of the default the program gives you. Use RomLister to get the list of mature games you want to get rid of. Output it to "File" and save that batch file in your roms folder. The go to your roms folder and double click that newly created batch file to delete those mature games. Then open mala and refresh your game list.
This will completely delete them, though. If you only want to temporarily move them, then you'll need to change your batch file command using something other than "del.%rom%.zip". (Someone else will need to chime in with the batch file command as I'm not sure if "cut %rom%.zip c:/mature" would work.