You can allow your Team Captains to set a password that is needed to join the team.
  1. Navigate to Fundraising > TeamRaiser
  2. Enter the name of the event in the search field
  3. Click Search
  4. Under the Action column, click Edit  
  5. On the left hand navigation pane, select Select Team Options
  6. Find the number for Password-Protected Teams 
  7. Mark the checkbox to 'Yes, allow team captains to assign passwords for admission to their teams
  8. Click Save
Note: You must have "Yes, allow teams to be created in this TeamRaiser event" under the Team Formation section marked for the above password protect option to save.