I downloaded a java 7 for linux 64x in my raspberry pi. then i realized there is a special java 7 for raspberry pi, so i download that one through this code
sudo apt-get update && sudo apt-get install oracle-java7-jdk
then i realized there is a java 8 installed already.
My question is that how can i delete the java 8 and the first java 7 ,and only keep the special version of java for raspberry pi.