Team captain can be changed in the admin panel :
1) Go to campaigns admin panel.
2) Click on the People tab and Teams tab under it.
3) Find the team from the list and click/dbl-click on the record.
4) Click Edit button on the pop-up.
5) In the Team Captain field dropdown menu, select the new team captain. In the dropdown, click on the previous captain's name from the list. This will remove the previous captain from the captains list leaving only the new captain. (You can also have multiple team captains, click on all the names that apply)
6) Click Save button to save the changes.
Note : The new team captain should be a team member to be selected from the dropdown.