How can I make sure that my Dropbox files aren't using my hard drive space?

Hi Larry1218! Thanks for posting on our Community. 

If you open your Dropbox folder, do you see green checkmarks next to your files/folders? If you do, then they're most likely taking up hard drive space from your computer indeed.

If you right-click on your files/folders instead, do you see an option to make them online-only? Selecting this option should replace your files with a placeholder that won’t take up hard drive space from your device (the full version of your files will still be stored on www.dropbox.com). Of course, if you wish to make a file/folder available offline again later on and sync it locally to your computer, you can right-click on it and choose the relevant option. 

After that, you can also change the default setting of your Dropbox app, so that new files you sync to your Dropbox folder are automatically made online-only in the future.

Besides making your files online-only, there’s also another separate Dropbox feature that you can use instead, which is selective sync. With this feature, you can opt to completely remove certain folders from your desktop app and have them only show on your Dropbox account online. 

Finally, please keep in mind that, if you wish to edit a file on your computer, then you’ll need to sync it locally again, make your edits and then unsync it, to prevent it from using your hard drive space.

Let me know, if that helps.