If you remove that, all Java based programs will fail to work. What you have now is just the runtime, which is only what you need to RUN Java programs. The JDK, or Java Development Kit, which lets you PRODUCE Java programs is quite a bit bigger.
Also, don't confuse memory with disk space/storage. They're two completely different things, and knowing the difference could save time, possibly even avoid having the wrong repair performed, if you ever need work done on your system. Memory is RAM, or short term storage; it goes away when you shut off your system. Disk space is permanent, or persistent might be better; it remains over successive power cycles.
To free up memory space on my dell xp I'm removing unnecessary programs. I'm not ever going to write my own programs - can I remove "jave 2 runtime environment standard edition"?