I don't have this years game yet. Had to move and no internet or computer so its hard to play the game. But from last years there is two ways to do this. Both are time consuming though. One will take about 10 years and that is just keep winning and building up your finances and the chairmen will eventually step down. Once he did he sold it to a tycoon so that was nice although at the time I already had the best team in the world.
You could always do what someone say earlier and just go in the red and the owner will then sell the team, but your finances will be in terrible shape and not always will you get a guy to pay off the debt.
To build your stadium or a new one, and I know it was in last years game you can actually build 2 stadiums at least with one team. After the first year the team built a new one and then 30 years later when my finances were in great shape they built a new one again. Stadium went from 11,500 to 22,000 to 45,000.
Basically you have to play a long time for a save and have great finances to get what you want. Also winning leagues and tournaments help as well.