In order to remove an Apple device from iCloud, be sure that the device has “Find my iPhone” turned off.

 1) Open “Settings on the device
 2) Choose iCloud
 3) Set “Find my iPhone” to OFF

 Using another device, login at using your iCloud credentials

 1) Choose devices
 2) Power the device off
 3) Click the “Delete” icon for that device

 The device should now be removed from iCloud.