Can I uninstall Java?
The answer is almost certainly yes—unless you're a Java programmer. It can't hurt to remove it if you don't need it, and can probably help.
I've been running without Java on the desktop for years. The only thing that I've needed to put it back for has been with one extremely "legacy" behind-the-firewall application.
There are some old corporate applications that still depend on Java in the browser. If you're in the situation of having to use one of those, don't mess with the software installed on your company system, because the IT Department probably has a required setup that you're supposed to use, and you can just use that. (What are you reading random blogs for? Call your company help desk if you have questions about that machine!)
For your own computers, the instructions for removing Java depend on the OS. On Linux, you can use the regular system package manager to remove Java. On other platforms you can read How do I uninstall Java on my Windows computer? and How to disable Java on your Mac.