Someone Pls,pls tell me how to unlink my device from Cydia Apps.

[iYeow]

I know how to link my paid apps from Cydia to my device but what if I sell my iphone, how do i unlink it, do I have to call Cydia to manually unlink it. No one seems to answer this question.
I am not joking, I am serious, I know quite abit of stuffs about jailbreaking but I can't seem to be able to unlink it. Even if I do a restore, it can still install all the linked apps from Cydia , I don't want the new owner to be able to use my paid apps and will also enjoy my future bought apps too.

[j3st3r]

I don't think you can unlink it, at least not in the few threads I read on here

[iYeow]

Ok, thank you .