Firmware password.

Coinsguru wrote:

Well, that is debatable, it belongs to my sister, she wouldn't take no for an answer. (Long story)

I thought i would ask here as it is very possible and easy to remove windows passwords.

I have never used a macbook before.

The previous owner needs to do this: What to do before you sell, give away, or trade in your Mac - Apple Support

Coinsguru wrote:

How do i get past the "Firmware" padlock after buying a second hand mac air? No receipt, no proof of purchase, have i been scammed?

You can not bypass the password. Think of how easy it would be for thieves if they could get past the password. Passwords would be useless if you could bypass them.

Return the computer.