Finished drinking 6 glasses of water first thing in the morning before food can aid in weight loss and detox? Is that true? Will excessive water harm?

Hyponatremia. Yes, forcing yourself to drink water can dilute the essential salts in your blood which mediate all the nerve signals in your body, so you can poison yourself with too much water! Sixteen ounces is plenty at the start of the day. You can gauge the appropriateness of the amount of water you are drinking if your urine stays pale yellow--never clear or deep yellow.
Little; Marketing. The human body, like all living creature open systems, is continuously doing detoxification; crucial to staying alive. Open system means everything the body is composed of is constantly changing; rates varying from extremely rapidly to very slowly. Most marketing depends on people not understanding engineering (life is the most complex) & promoting overly simplistic ideas of little/no truth.
Detox is crap. There is no reason to "detox" your body. Your body does that naturally every time you go to the bathroom. The myth about needing detoxification is internet junk, designed to sell books, pills, and other chemicals which may harm you. Drinking that much water is unnecessary and can be harmful. Do everything in moderation and don'g get medical information from the internet.