Clean A USB Drive on Windows

 Click your Start Button, then just type cmd

Form the resulting list, right click Command Prompt and choose 'Run as Administrator'

Run this command and hit Enter:

diskpart

Run this command and hit Enter:

list disk
(Make note of the disk number for that flash drive and enter it into the next command - replace disknumber)

Run this command and hit Enter:

select disk disknumber

Run this command and hit Enter:

clean

Run this command and hit Enter:

list disk

(Make note of the disk number for that flash drive and enter it into the next command - replace disknumber)

Run this command and hit Enter:

select disk disknumber

Run this command and hit Enter:

create partition primary

Close Command Prompt and go back into Disk Management