Usb flash drive write protected cannot format

Write protection is a function that not allows one to transfer, write or delete the inner data on a drive, except reading. Therefore, you have to disable the write protection before you can format it.
To remove the write protection:
http://www.itrelated.info/remove-write-protection-from-...
Is there something important data?
If you are forced to format it for somehow, you could try an unformatted drive recovery freeware to get back your data before the format.
To get the unformatted drive recovery freeware: http://blog4mark.blogspot.com/2013/01/unformat-memory-c...
To format your drive like this:
Right click “My Computer” =>Select “Manage”=> Choose “Disk Management” => Right click your drive on the list => format it.