卸载JDK

$ java -version
java version "1.8.0_66"
Java(TM) SE Runtime Environment (build 1.8.0_66-b17)
Java HotSpot(TM) 64-Bit Server VM (build 25.66-b17, mixed mode)
$ ls /Library/Java/JavaVirtualMachines/
jdk1.8.0_65.jdk jdk1.8.0_66.jdk
$ cd /Library/Java/JavaVirtualMachines/
$ sudo rm -rf jdk*.jdk
Password:
$ ls -lah
total 0
drwxr-xr-x  2 root  wheel    68B  1  1 09:00 .
drwxrwxr-x  4 root  wheel   136B 12  8 21:56 ..
$ sudo rm -fr /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin
$ sudo rm -fr /Library/PreferencePanes/JavaControlPanel.prefPane

如果想删除整个Java目录，删除前应该检查Java目录的内容：
$ sudo rm -rf /Library/Java