I know about that.Do you know if the "Find My iPhone" feature has been set-up?
If so, it's possible.
http://support.apple.com/kb/PH2701
Someone has my brother's iPhone.I am quite in the know about iPhones and iOS BUT it seems too suspicious to me that you want to remote wipe a iPhone and not tell us why.
As Depravo hints, It's not your phone is it you wanna wipe someone else's phone and in that instance I will not help