1. Download MiniTool Partition Wizard Home Edition (ISO) from this
site (download Bootable CD ISO).
2. Download Yumi Multiboot USB Creator
here.
3. Run Yumi. Select drive, tick format, select Partition Wizard, select ISO, click Create.
4. Wait until the process finished.
5. Now reboot your PC from the USB pendrive.
6. I have tested to format external drive, but its not detected (why?)