any body can help me, how to delete/remove themes in N73 ?

I've installed some themes in my mmc, i need to delete/remove some, but some of my themes are not visible in app. manager, how can i remove them ?

I've try to find the file with Y-Browser ? but I cant find it, what kind of file and extension of the theme?

Do Y-Browser can find the file ?

Please help me ?