edit: I have found a solution: Log into www.cloud.com. Goto "Find My iPhone" and wipe the device. I cannot sell my iPhone 5 (iOS7 beta 6), because I cannot turn off "Find My iPhone". I want to do a downgrade, but when I try do deactive "Find My iPhone" in the settings a error message appears. I cannot flash a firmware cause iTunes says I musst deactivate "Find My iPhone". Also a reset of my iPhone to factory settings is impossible. An error message appers that a reset isn't possible cause of iCloud. My iPhone 5 seems to be bricked it I cannot sell it, because I cannot untie my iCloud account from the device.