Why not just download one of the zillion options for live boot media (thumb drive, CD/DVD ROM) - boot from one them, copy the files you want to a network or cloud drive or an attached external drive, you're (half) done.
(If the partitions or user folders are encrypted, then it's a harder nut)

As for wiping - how sensitive information the drives have? There are different solutions for simple wiping/reformatting to mil spec data erasure. If you want to play really safe, you should physically destroy the drives. Old skool spinning ones can be killed by frying their electronics and/or driving a few holes in them (I don't think anyone would go to the trouble replacing the electronics to get to the data). SSD drives might also not like holes drilled in them.