Messing around with pre-loaded apps can be tricky since you can lose functionality. Also, we'd need to know exactly which phone and carrier you're using. But as a general rule of thumb you can try the following: If you see it but don't use it, chances are you won't need it, so go ahead into the Application Manager and find the app you don't want. If it has an UNINSTALL button, you're in luck: your phone doesn't need this to work properly. Good riddance. If it has an UNINSTALL UPDATES and then that turns into a DISABLE button (or the latter is there from the beginning), it means your phone MIGHT need this for some functions but it's not critical. You cannot uninstall them to free up space (unless you root and you manually get rid of the files, which is a lot riskier), but at least they won't be active at all in your phone using resources. If you don't see either of these buttons, it means that either the manufacturer or the carrier have deemed this process as critical and must always be running. This doesn't always mean that it IS a critical process, just that they don't want you to get rid of it. In this case, rooting would be the only way to make them go away, with the inherent risk this brings.
DISCLAIMER: If you do go the rooting way, I strongly suggest you really research your phone model and carrier and find similar lists of 'safe to delete' apps. Delete the wrong stuff, and you might end up with a crippled phone and a voided warranty. You've been forewarned.