Plz help downgrade SPL

[Vaness99]

I installed Cokeman. It appears on the rainbow screen. I have not installed radio. The directions I've been given require me to put it on my memory card which I do not have- I don't even see a slot for it on my phone. All the threads I've read say that it is risky to downgrade after installing the radio and or the GPS. I have not done either. Plz tell how to downgrade from this point. Plz I am desperate. I am way in over my head in all this. I just want my phone back to normal PLZ PLZ help.