Hey
@Bossa1, thanks for joining us on the Dropbox Community and happy holidays!
When you say that you unsynced your computer, can you please describe the steps you followed?
Also, before you did that, did you disable the computer backup feature on your Dropbox application?
If not, I suggest you make sure that the Dropbox app is working again and then
disable computer backup.
Once it's disabled, you should be able to delete the folders from Dropbox.
Let me know how it goes.