People still store contacts on their SIM? If you lose your phone, you lose ALL your contact information...and you have to post one of those annoying "Please send me your number" posts.
I'd suggest to enter the contact info into your outlook address book for your Microsoft Account.
But to answer your question, you just go to the People tile, click the "..." and then Settings. There is a "Filter My Contact List" option and that is where you remove accounts from your view.