Remove Dropbox completely from my computer

I had the same problem. It came to my attention because some other apps stopped working after I backed up my computer on Dropbox.  I fixed it eventually only by working with Apple support for several hours. Luckily, Apple support will respond to requests quickly and work with you in person to solve individual issues, which Dropbox won't do unless you have the highest level subscription. Basically I had to recreate my original file structure and copy the files into it from the Dropbox app. I also had to redo all the aliases and shortcuts I had set up to access key files quickly.

The problem with getting off Dropbox is created because if you download the app, Dropbox lures you into backing up all your files on Dropbox, and then when you click yes, rearranges the structure of the files on your computer. They don't give you any warning ahead of time that it is going to happen. They don't have an undo option to reverse this operation if you change your mind. Once I had disabled the option and rearranged my files so that everything worked again, Dropbox still tried to get me to do sync with it again and also seemed to do strange things to my Desktop, until I removed all Dropbox applications from my computer.  

Dropbox is still a useful tool for sharing files if you work only via the web without downloading the app. It's no longer a viable backup tool in my opinion.

Thanks for clarifying that FrustratedUserB 

Could you also clarify which steps you're following and send us a screenshot of the exact error you're getting?