How can I get rid of offers4u adware?

On some web sites -- including, perversely, the Norton support site itself -- I am getting scrolling banner ads across the top of my browser.  The banner says that it is called Offers4u.  It mostly appears when I go to shopping web sites, but also some others such as the Internet Movie Database (imdb.com)  This seems to occur primarily when I use Google Chrome, but happens in other browsers as well.  I have been unable to remove it either with Norton or with other products such as MalwareBytes suggested on web sites discussing this adware.  I have attached a screen shot of this web site with the offers4u banner across the top of it.