Note: Please, do this before deleting any files/ folders from your computer.
1. Click on Dropbox icon at the top-right side of the screen.
2. Click on your initials and then click on "Preferences."
3. Click "Sync"
4. Click "Select folders"
4. Deselect all folders that you do not want to sync with your computer, and then click "Update."
Once that's done, if any file is added or removed from the Dropbox folder, it won't show on your computer.