Usually teams in level 1 will give up halfway through so they will remain inactive through level 2 and level 3 and they will eventually get deleted. The higher you go, the more active managers there are. There's always a ton of level 3 inactive teams but they will get deleted next season.
That is why level 3 is the easiest in the whole game. Ton of inactive users and abandoned teams so make the most of it because it won't be that inactive as you progress.