An easy way is to do this is the use of diskpart.exe
Just type the following:
- list disk -to find out the number of the disk
- select disk ### - to select the disk you want to clean
- clean - to delete all partitions (be careful with this command :) )
After the cleaning the easiest way to create a new partition is to use diskmgmt.msc or just type in the following commands:
- create partition primary
- select partition=1
- active
- format fs=fat32 QUICK
- assign