Going From PSP CFW 5.50 Prome-4 to OFW Help!?

I have a phat psp (10001) currently running CFW 5.50 Prom-4 and I want to remove it and go with OFW. I don't care if CFW is better but i'm having problems removing or downgrading it. I tried hellcats recovery flasher and it kept giving me errors. I've also tried downloading the recovery file from playstation but it gives me an error that i'm running 9.90 so there is no need to update. It's driving me nuts and some help would be awesome. I've been googling it for hours now with no luck.