ok, so you just bought a used cisco catalyst switch and you want to reset it to the factory defaults erasing all the current configurations right?

well, i getting ready to sell on ebay a used cisco switch and i want to erase all my current configuration to sell it.

it only takes three commands to reset your switch. very easy, here are the three commands:

1
erase startup-config

Erasing the nvram filesystem will remove all files! Continue? [confirm]
hit ENTER to confirm

2
delete flash.vlan.dat

Delete filename [flash.vlan.dat]?
hit ENTER to confirm

Delete flash:n? [confirm]
hit ENTER to confirm

3
reload

Proceed with reload? [confirm]
hit ENTER to confirm

after you reload,