Service [Q] Downgrading from 4.4.2 to 4.3. How to?

hello guys! I own a SGSN2 and i upgraded it to 4.4.2 and i want the 4.3 back.
I heard aboout the KNOX protection and now i am affraid that something back could happen if i use odin to flash a 4.3 official software.
I don't care about warranty, so give a solution, please.
Also, in the KNOX app, it seems like KNOX may not be installed or something.
It requires a 160 MB size content to download .
What should i do, guys? ?