I weigh 245. if i work out 4 times a week at the gym for an hour each time and take long walks on 2 other days how long will it take to lose 100 lbs?

Depends: This is entirely a function of calories-in, calories-out. If you increase your eating, you'll gain. It's impossible for most people to control eating very well. Only a major lifestyle change or bariatric surgery will result in permanent weight loss. My hope is you'll find friends who have aerobic-fitness-focused lifestyles who can guide you; it helps restore healthy appetite control. Good luck.