Several times each day I use the MANAGE WEBSITE PREFERENCE option to clear the website data to websites that I have visited during the day. Presumably I am clearing out the cookies that websites leave when I visit (or it seems, sometimes just get close to - like seeing the name in a google ad.)

I could use private browsing (Safari is my default browser) even in Safari but I choose not to do that because I participate in a few forums and use google mail so I would need to log in every single time to all these everyday website which I frequent.

Up until yesterday - just clearing selected websites on my "manage" page and "removing" those web sites took them off my website history forever (or until I went back, of course).

NOW I have one website which just cannot be cleared off. I cannot select it independently (as with all the others and as I have always done). It just cannot be deleted. If I select ALL the website history it clears the cache for a few seconds but nearly immediately that one web site comes back as if I am always linked onto their site.

Please - any idea how to permanently delete this leech? It is a check printing company - NOT the one I use and not one I will ever do business with or investigate their site. In fact, I don't think I have ever been to their site.

Any help will be greatly appreciated. BTW - my operating system is OS X Yosemite version 10.10.5 - if that is a useful bit of info.

Thank you.