Most pieces of metal are screwed onto the bike for a reason. If one piece is hitting the chain ring, then something is wrong. Depending on what it is, just removing the piece of metal might not be safe. Get an experienced cyclist to look at your bike and tell you what's going on. It's not hard to find experienced cyclists. They hang out in bike shops. You can easily recognize them. They're the ones drooling over the most expensive bikes in the place.
HTH