My father passed away in May. He has a Dell Inspiron 530 that is going to be sold at the estate auction. We need to wipe the memory clean and reset it to new. However, we cannot get past the password screen for administration. He did not have a network administrator, it was just used for home, mainly email. We tried bypassing it, but it just says we cannot go any further without a password.

How can we wipe this clean so no information is passed along? He no longer has internet since his death