Can't get rid of double unupdated Shockwave Flash after reinstalling FIrefox

I want to remove this in my add-ons: "Shockwave Flash is known to be vulnerable and should be updated. Update Now." "Shockwave Flash 15.0.r0" When I click update, FIrefox has blocked it: "Flash Player Plugin 14.0 to 15.0.0.242 (click-to-play) has been blocked for your protection." But I want to remove it completely - I have a 2. Shockwave Flash add-on that is an updated version. I removed Firefox from my PC, restarted, reinstalled Firefox, but STILL, there is the SAME VULNERABLE SHOCKWAVE FLASH in the add-ons - how can this be?? Why is my old add-ons and preferences here after I have removed and reinstalled Firefox?? Why does FIrefox keep my info? How do I remove this old add-on? Or do I have to start using another browser in stead of Firefox?