How to get rid of luckywinners.com-onlinelink. It's on my face book page and won't allow me to do anything with out pushing ok!

I Have an iPad ios8.4.1

i opened up something a friend had postend on Facebook and a post from luckywinners.com-online.link come over Facebook page and won't allow me to do anything, it wants me to push the ok button. I have gone into setting and went to safari and cleared history but this didn't work for Facebook. Can you please help?