How To Remove Write Protection on a USB
To remove the write protection, simply open your Start menu, and click on Run.
Type in regedit and press Enter.
This will open the registry editor.
The next step is to navigate to the following path:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorageDevicePolicies
Double-click the WriteProtect key located in the right side pane and set the value to 0.
Go to the Data Value box and press OK
To finish, simply restart your system, and then reconnect your USB pen drive to the computer.
Kilde:
https://ccm.net/faq/4214-how-to-disable-write-protection-on-a-usb-key