I have been searching the internet for a solution to this same problem for like a week now and I finally figured it out.
I already tried the obvious, control panel, uninstall; wrench, tools, extensions.
I also tried the task manager and looked under processes for it and it was not there.
I even tried the program files, common files, etc, etc... you get the picture.
So here is the solution that you are looking for:
Open Chrome, you'll see your trusty annoying little Yahoo tab
Click on the wrench
Click on settings
Under "Sign In" you will see "On Startup", the third circle should say:
Open a specific page or set of pages. Set pages
Click on Set pages and you will see the little bastard! Mouse over Yahoo and delete that punk once and for all!
That's it, it's pretty simple once you find it.
Hopefully this helps you, if not I don't know what the problem is for you.
this worked! thank you so much