Accidentally enabled Backup - how can I undo this to free up my space?

I'm using Dropbox (free version) for a few years now. I never upgraded my plan simply because I don't need as much space. In the past couple of weeks, I have connected two laptops with my account. I don't know how or why, but Dropbox by itself, and I'm not joking here. I started to back up my files?! I noticed it because I received a notification on my phone saying that I had run out of space. I had a folder loaded with (*.exe *.xml *.7z *.rar) ect... I don't know if that can create problems? I immediately paused the process, and I unconnected the two laptops from my Dropbox account. I then tried to clean up my Dropbox account. Currently, I have a folder in my Dropbox that comes from one of the laptops. I tried to erase it, and it was impossible! Now that I have already removed my two laptops from my account, I'm working with my cellphone trying to erase files that were originally uploaded from another source. I have a copy of all these files, and they're all secured protected by passwords. I can't resume the backup. The target laptop is no longer in my Dropbox account. Furthermore, the laptop has been formatted! So, I think, I'm going to have to erase my Dropbox account unless someone from Dropbox can erase the folder and files in question!?Thank you for your help, I hope I can solve that problem because it takes all my space thank you very much.