How can I get sunscreen stains off of concrete?

A degreaser might work. If it isn't too old put down something that will absorb it, like baking powder or flour.

You could try using a power washer. Or, you could use a bleach cleaning solution. (Buy a spray that contains bleach.) Just make sure you protect your skin and eyes.

Put down Dawn, Tide or another grease fighter, rub it in a bit with a broom or brush and let it sit for a little while. Rinse with a power washer or strong setting on a hose. If it has been there for a while, it may take a few times with the soap, brush and rinse.

I would try some Dawn and water. Maybe the dawn will lift the grease in the sunscreen.

You can get a degreaser from your local hardware store, grease stains can be hard to remove.