I recently spilled some brake oil on my brake pads and now they barely work, and they squeak (which I believe is normal for contaminated pads.)
It's at your own risk, doesn't always work, and may be a waste of time, but burning it out is the way to go if you have to do it. Looking past the global northy sort of time/money/risk/hassle equation, it's a pretty reasonable fix. I have no idea what the potential ill effects on braking power or trustworthiness of the pad material might be, but this approach is fairly common and major issues don't seem to result.
If possible, clamp them in a vise gently by the tabs, then use a heat gun or hair dryer to apply slow, even heat. Because the whole problem is the pad compound has some porosity to it, you're trying to heat it evenly all the way through. You'll get some smoke and are basically trying to heat it until it stops smoking.
Clean the rotor with something suitably nasty. In these cases of known mass oil exposure, it's good to take the rotor off completely and do something like a hot water and dish soap type bath, followed by thorough rinsing, followed by whatever sort of zero-residue reproductive harm spray. If it doesn't get a bath it can be hard to make sure everything is cleaned out of the windows.