Start up a new Franchise with any team. Go the calendar and scroll to the last month of the season. Highlight the last game and press the button to Sim Game, which will also sim all the previous games as well. Back out and Advance to the Postseason. It doesn't matter if you made the playoffs or not. If you did make the playoffs, keep pressing Sim Game until those are done as well, and then back out and Advance to Next Season. At this time it will show you if any of your players retired. If none did, repeat the same steps to simulate another season. Keep doing this until you finally get some retired players at the end of the season and the trophy will pop immediately.