The first thing you should do is this:
"adb shell
cd /system/app
ls"
this will give you a list of all apps loaded into the system folder. I STRONGLY RECOMMEND if you have never done this before, to copy the folder to your pc, in case you delete something you shouldn't have:
"adb pull /system/app (drive\folder location)"
Once you're done copying everything over, you can go through and delete the apps you don't want individually:
"adb shell
cd /system/app
rm -r (file name).apk"