Remove MBR from USB flash drive using Windows

Solution 1:

diskpart
list disk
select disk X
clean

(X = The number of the disk)

Go to Disk Management and create a new partition on the disk, it should then work as normal again.

Solution 2:

 diskpart
 list disk
 select disk X
 list partition
 select partition Y
 inactive

• X = the number (not letter) of your USB disk, as indicated by the list disk command.
• Y = the number (not letter) of the bootble partition, as indicated by the list partition command