Wipe partions (factory reset) from Poweredge 2950 with ESXi installed?

I'm trying to "factory reset" some old poweredge 2950's that I have and currently have ESXi 5.0 installed on them. I want to completely wipe the servers so that nothing is installed on them. I'm familiar with wiping partitions with windows servers, but not so much with ESXi OS installed. What is the easiest way to completely wipe the Poweredge 2950?