xmarks box on Laptop Win 8.1

I am not able to download the utility as I am sending this query on my desktop.

I never registered or signed on to Xmarks. I now have an Xmarks white box with blue trim and "log in to Xmarks" on my laptop. I cannot access any of my sites, email or do anything on my laptop due to this white box on the screen. I am not able to type into this apparently "sign in box". I can move this "Xmarks" box around my screen but that is all I can do with it. I do not know where it came from or how it got onto my screen. It was there a few weeks ago and then it disappeared, now it is back again.

I am able to get into Control Panel, I tried to delete Xmarks in Control Panel but it is not listed in the programs so I could not delete it from my Laptop.

Please help me get rid of this Xmarks box for good.

Gram