Modify KNOPPIX

Hi.
I need to modify KNOPPIX programs and make it bootable usb.
Well. I have a previous Linux system and i download KNOPPIX. I read remastering & customising documents but i read that you need to boot this and modify from there. It's possible to do with extract all files with "extract_compressed_fs KNOPPIX /knoppix/" and make the same??
Another question. If i want to uninstall all programs of KNOPPIX default how can i do???
I know that these general questions its complicate to explain but i would like some guide or similar that explain something about it.

Thanks for all.