How do I cancel my Dropbox for Business trial?
To cancel your 14-day Dropbox for Business trial, sign in to your Business account and go to your team's Account page. You'll see a link for Cancel Dropbox for Business in the bottom right, which you can click on to end your trial period.
If during your trial you connected a personal and a work Dropbox, your Dropbox for Business account will become a second personal Dropbox. Your original personal Dropbox will remain the same.