How to Remove Oracle Java JDK 6/7/8 Ubuntu

Check installed JDKs list

sudo dpkg --list | grep -i jdk


Just check Java plugins with firefox

about:plugins


Remove the desired package

sudo apt-get purge oracle-java7-installer



Check whether the removed JDK is still there.

sudo dpkg --list | grep -i jdk



Just check Java plugins with firefox

about:plugins