You can delete the files directly from ~/Library/MobileDevice/Provisioning Profiles
Open finder, ⌘-Shift-G, and paste in the above path. Restart Xcode afterward.
An alternative way is to use the Apple Configurator (Mavericks) or iPhone Configuration Utility (pre-Mavericks) which displays provisioning profiles installed on your system and allows you to remove them (select and press delete key).
Apple Configurator Apple Configurator makes it easy for anyone to mass configure and deploy iPhone, iPad, and iPod touch in a school, business, or institution.
