Unallocated memory in drives

This is for those who got unallocated space in their pendrive in spite of numerous formating.
Go to start.
Type cmd.
Type diskpart.
It will open a new window.
Then type list disk command to find your USB flash disk number.it should be same as disks number in computer management tool .It was 1 in my case .
Choose yours to work with .
Type select disk(num) command
e.g. select disk 1
The next step is to clean the volume therefore type command clean to do that .
The last step is to create the partition,type command create partition primary .
Remember doing this removes all data of the drive so maintaining backup is recommended 
This is how u remove unallocated space ..