Once you click on 'Create Team' you may return your team to the draft center before the season starts by clicking on the red 'R' in the Team Center. This will immediately remove your team from the league and place the roster back in the draft center. You may edit your team and/or change leagues here. To prevent unfair advantages, this is why team rosters are not available to be viewed by users (except the commissioner for Theme Leagues) before the league has filled. Once the league has filled and the schedule has been generated, the only way to adjust a roster is through the GM's Office.