code needed for a dab radio ive sold help

[jamesey]

hi ive recently taken my 2012 dab rcd 310 out of my Passat and bought a similar one that has a few different functions on it for the aux , I think I know the code for the one ive sold but not too sure , ive fitted the new one ive bought and put the code in given then put the sold one back in and it remembers the code from last time , how can I get it to reset so I have to put the code ive found in,,,now ive sold the radio its a must lol