Reformating Apple hard Drive Used as an External

[Gator24765]

I have an apple hard drive 250 gb. That was takin out of my MBP because i upgraded to 500gb.

I bought a hard drive enclosure for the old one. When i plug it in via USB it shows folders like applications, library, users etc.

How do i reformat this hard drive so that it is completely empty so i can use it like a normal external hard drive?

 

[splitpea]

Disk Utility.

 

[Gator24765]

Thanks