Dropbox 'selective sync' function remains files only in the webstorage and delete the files in my local computer. How can I do the opposite? I want to keep some files only in my computer but not on Dropbox web folder.
Copy the folder outside the Dropbox folder, then disable that folder in Selective Sync. If you copy the backup to the same place and Dropbox will ignore that folder from syncing. (Later on, if you enable it again, it will upload as a conflicted copy.)
Read this article: Dropbox - How do I select which folders to sync to my computer?
If you want to delete the copy in Dropbox's cloud but keep the one on your computer and turn off syncing for that folder then you need to:
- Move the folder outside the Dropbox folder
- Create an empty folder with the same name in the same location
- Disable that folder in Selective Sync
- Move the backup back to the original location
That will result in that folder's contents being removed from all other computers syncing to your dropbox account. The folder will only exist in your current computer and will not be synced or backed up to dropbox's cloud storage.