Remove ubuntu on macbook

I just inherited an old macbook a1226

The os is single Linux 1.99-ubuntu3.10

IT is broken (os) for some reason

(I grow veggies on a permaculture farm... Dont' task me why... ;) )

I'd like to restore IT some sort of OS X native os installed onto IT.

I have tried option c, option r, c on boot to boot on snow Leopard cd... None worked

I am stuck on grub command line and i am lost.

If one of you has an idea, he will be saving my life..

Cheers

lorena