If you're an administrator of a Dropbox for Business account, you can remove someone from the account at any time. Once the person is removed from the account, you can reassign the license and invite another person to the Business account.
When you remove a member, this deactivates the user's account. The user will no longer have access to the account, and shared links created by the account will be disabled. Dropbox will also stop syncing files to the user's computers and mobile devices. Files that have already been synced to the user's Dropbox folder can be removed from any device with an active internet connection using remote wipe.
In the process of removing a member from your team, you can also use account transfer. This option allows you to move all of the files and folders in the person's work Dropbox to another person on the team. All of the files and folders that are in the former member's work Dropbox at the time you initiate the transfer will go to the recipient's Dropbox. Additionally, Dropbox will look to preserve any file sharing relationships, so any shared folders or folder ownership will also be transferred.
This article refers to a feature unique to Dropbox for Business. Dropbox for Business is designed for projects, groups, and other organizations that want to share the same Dropbox storage quota with all of its members. If you're interested in learning more or want to sign up, visit the Dropbox for Business webpage.