I have manipulate the schedule in my league for the teams who wanted the games spread a little more and not have 3 off weeks at the end of the season but I realized the changed schedule will stay the same for the following seasons. How can I get back to the "normal" league schedule to avoid teams having the same schedule every season?

I don't think there is a way to do it in game. I'll have to add that into a future version. For now feel free to open a support ticket and attach a link to your .bin file and I can reset it manually.