If you need to downgrade your Dropbox Plus or Professional subscription back to a Dropbox Basic account, follow the instructions below.
Note: If you downgrade, you'll still finish any time remaining on your current subscription before the Dropbox quota granted by the upgrade expires. After downgrading, your account will no longer automatically renew and no further renewal charges will be applied from that account.
Downgrading to a smaller Dropbox won't delete any of the files already there. Please be aware that Dropbox will not delete any of your files when your subscription is downgraded. If downgrading causes your account to go over quota, your files will no longer sync between the devices you've connected to your Dropbox account.
Your Dropbox folder will only sync files between your account and connected devices until you reach or surpass your account's storage quota. You will not be able to add any new files to your Dropbox or restore any files removed from your Dropbox until there is enough free space in your available quota to do so.