how to delete old provisioning profiles from mac OSX lion

hi everyone

i want to delete my old provisioning profiles

i did it from prgarnizer of xcode but it give me error when i run app on iphone

"This provioning profile have no valid signature"

i search about it then get to know that it store in

library->mobiledevices-provisioning profile folder

but i had a problem i.e my mac mini with mac osx lion 10.7.2 don;t have that directory

so please let me know that where it is in that

thanks in advance