Cancel sync from itunes to iphone?

I have attached an iphone and now the music library on that device is in sync with my music library. There seems to be no way to cancel this process.
The example is that on the iphone for the music, there are greyed out listings for music currently in sync and they can't be canceled.

Added (1). Thanks awesomiz. Question resolved. The phone was not mine and the owner and I have different tastes in music.

I think your apple mobile service got hanged, it was happnd with me too… I went in task mngr, goto services… N search for apple mobile service.n start it again, n you can cancel your sync… Or you have to hold power button n slide