Spyware help.... PLEASE!

I downloaded MacKeeper accidentally when it was attached to a school assignment source. Once all the pop-ups occurred I realized something wasn’t right. I know now that it is spyware and I want it off my computer. I am fairly new to Apple products and I don’t need anything complicating my Mac time. Any who, now I am not able to get rid of it. My kids helped somewhat but it keeps coming back. Can someone please help me? Or is this a job for the Genius bar?

Thank you