Wash collard greens thoroughly in cold water; drain well. Remove and discard stems; trim bruised leaves. Coarsely chop leaves to measure 6 cups; set aside.
In a large saucepan cook bacon until crisp. Remove bacon, reserving drippings in saucepan. Drain bacon on paper towels and set aside. Add water, pork hock, onion, sweet pepper, sugar, salt, cayenne pepper, and garlic to saucepan. Bring to boiling; add chopped collard greens. Reduce heat. Simmer, covered, about 1 1/4 hours or until greens are tender. Remove from heat. Remove pork hock. Cover greens; keep warm.
When cool enough to handle, cut meat off pork hock. Chop or shred meat; discard bone. Return meat to greens mixture along with cooked bacon; heat through. Serve with a slotted spoon. If desired, sprinkle each serving with a little vinegar.