Team names are managed at a season level, and can be edited from the seasons tool. To launch this tool, expand the League Configuration menu and click Seasons. Select the season you'd like to edit a team name in, then click View. From the Conferences, Divisions and Teams box, click the team name. Make the required changes in the dialog box on the right and click Save. 

If a franchise moves to a new city, or changes their team name, add the former team to the season, then make the appropriate city/team name changes. This will be reflected in this season and all future seasons, but will not alter past season names. 

Note: Team names must be consistent within each season. Leaguestat does not support mid-season name changes.