Only players can change their email addresses in RosterBot, not managers.
If your player’s email address is about to change, tell them to login to the RosterBot web site and head over to their player profile. From there, players can change any of their contact information whenever they like — and this is automatically reflected on each of the teams they play for.
Alternatively, managers can select their players within their team’s Players page and chose to ‘Add Shared Users Email’. This will share this teammates membership with another user.