How-To-Geek has published an article, Java is Insecure and Awful, It’s Time to Disable It, and Here’s How. The article does a satisfactory job of explaining why you should be concerned about running the Java Run Time Environment - or even keeping it installed. It then explains how to remove or disable Java RTE from popular browsers, but it doesn't show how Safari users might do this.
Fortunately, it's straightforward:
From the Safari menu, pulldown and choose Preferences...
Choose the Security tab
Uncheck the box labeled Enable Java
Close the Preferences Window
This is essentially the same information you'll find at Apple Support, under the title How to disable the Java web plug-in in Safari. The image capture Apple uses is different from what you'll see if you're running Safari Version 6.0 (8536.25 or 7536.25) but disabling Java is unchanged.