Remember to make a backup before doing this just in case you want to undo, maybe you accidentally delete something important.
If you don't want to run anyone's ROM, without scripts you can type into adb
What you have done there is mounted the system as writable, allowing you to delete or modify stuff. Changed directories from / to /system/app (will save typing if you have more than one app you want to delete). "ls" will list the contents of the folder you are in, because you will need the exact name of the .apk capitalization and all.
mount -o remount,rw -t yaffs2 /dev/block/mtdblock4 /system
So onto the deletion:
You can type ls between each one to get an updated list.
After you are satisfied with your deletions type
mount -o remount,ro -t yaffs2 /dev/block/mtdblock4 /system