I want to free up space on my computer but I still want to keep the files on Dropbox. If I delete them from my PC’s Dropbox folder do they get deleted off Dropbox as well?
Yes, the files get deleted from Dropbox as well. However, there are two possibilities to overcome this:
Set the Dropbox app to sync selectively and disable sync for that particular folder that you want to keep online, but delete its content offline.
Use the restore feature for the deleted files.
If you want to restore any deleted files, keep in mind that Dropbox saves a history of all deleted and earlier versions of files for 30 days for all Dropbox accounts. If you purchase the Packrat add-on for your account, Dropbox will save your files for as long as you have the feature.