Few days ago a new Java vulnerability has been discovered that affects all versions of Java 7 on most browsers. Luckily Oracle addressed it quickly by releasing an update. Since I previously had JDK 1.7.0_04 installed, I had to manually switch to use latest version by going to Applications > Utilities > Java Preferences and changing active version in the drop-down.
I wanted to remove the old version from my Mac, since it was unlikely I’d ever use it again. Unfortunately Oracle help page I found did not offer the solution. Luckily this turned out to be rather easy – all you need to do is go to Mac HD / Library / Java / JavaVirtualMachines and remove VM file that you no longer need (jdk1.7.0.jdk in my case).
Hope that helps.