Once you've unlinked a device, it'll stop syncing new changes from your Dropbox account. Note, if the device you've unlinked is a computer, previously synced files remain untouched. ... When you unlink a mobile device, files will automatically be removed even if they had been favorited for offline access.
How do I unlink Dropbox without deleting files?
Dropbox will only delete the files that are not used in a few months by the user. To remove files from dropbox without deleting them from your hard drive, you need to create a copy of the same and move it out of the local Dropbox account.
Will I lose files if I uninstall Dropbox?
Uninstalling the Dropbox desktop app will not delete your Dropbox account or remove the Dropbox folder from your hard drive.