If Resellers used their own username, password and email to purchase the Dropbox subscription (and the Reseller does not belong to another Dropbox Team), then Resellers will automatically be identified as the ‘Team Admin’.
In order to reassign the Team Admin role follow these steps:
1) Create an ‘Admin User’ (REMINDER! DO NOT assign the Dropbox subscription while creating this ‘Admin User’)
2) Assign the role of ‘Team Admin’ to the ‘Admin User’
3) Re-assign the Reseller’s role or if you want to free the license unassign the Dropbox service for the Reseller
Click on the links for detailed instructions.