old computer

I know its been a long time since i posted here but i was cleaning out my attic and i found my old computer, which is very nice but it doesn't really function because of all the shit i have on there and i got a ton of viruses and shit. so my question to you guys is, do you know how to reboot like the entire computer? like reset it to its default settings. any help is appreciated.

i got a ton of viruses

Lay back on the porn will ya? j/k

You will need to reformat your computer.