Clear switch password (and config)

My company just purchased a pair of Foundry ServerIrons and a Summit24 switch from a company that was going out of buisiness. All three devices still have passwords set on them. We are trying to get in touch with the original owner to find out about the passwords, but that is likely to take a while.

Can anyone tell me if there is a way to wipe the configurations of these devices without knowing the passwords?