I have ran into a small problem with my android tablet, it is a samsung galaxy tab 8.9 p7310

About a year ago i rooted it and installed CWM + CyanogenMod 9; i also encrypted the tablet. When i go under security the encrypted button is grey and i cannot click it, when i go to disable pin/password lock to none i cannot click on them and it says disabled by admin,encryption, credentials...

I cannot update my ROM because the SDCARD is encrypted and recovery cannot mount it so i am looking into alternatives, how can i format the internal memory in such a way as to reload the ROM; i don't care about the data stored on the device. I have looked into nvflash but i am unsure how it would help me, is there an ADB format command?

if anyone can point me in a direction it would be much appreciated!

thank you :)