can i disable cels with ecu flash

[polish man]

iv got a 04 wrx tuned on utec i just want to get rid of the po420 and put it in readiness mode for emissions testing. im unable to get romraider workin on my labtop and ive read ,changed my image and flashed it in but its not workin keeps sayin same image. is this doable only with ecu flash, thanks for any help.