How do i start fresh with linux??

Ive been experimenting with debian adding s/w changing configurations etc. I want to undo all that and start my beaglebone like when it was fresh out the box. How do i do that? also whats the term for doing this what do you call it???



So all the files and software, etc. is stored on the eMMC chip on the BB? Does it take the role of the hard drive on a PC?