As a follow-up from "Switching between Java 6 and 7 on OS X", here's how to remove Java 7 entirely:
# First the JDK
cd /Library/Java/JavaVirtualMachines/
sudo rm -rf jdk1.7*
# And now the JRE
cd /Library/Internet\ Plug-Ins/
sudo rm -rf JavaAppletPlugin.plugin
cd ../PreferencePanes/
# First the JDK
cd /Library/Java/JavaVirtualMachines/
sudo rm -rf jdk1.7*
# And now the JRE
cd /Library/Internet\ Plug-Ins/
sudo rm -rf JavaAppletPlugin.plugin
cd ../PreferencePanes/
sudo rm JavaControlPanel.prefpane
And that should be that.
