Can't delete backups that have filled up my Dropbox

AceConrad​ I can clarify what is happening with your external drive backup and what options you have now.

After completing a few checks of your account internally, deleting an unlinked device from your account likely won't help you delete the backup files.

External Drive Backups are read only. You cannot remove individual files or folders from them on the web or from another device. The only way to change what is included is from the original computer that created the backup by adjusting its Backup settings. Since you no longer have that machine, there is no way to trim or edit the backup.

At this point you have two possible paths:

1. Delete the entire external drive backup
   This is the only supported way to free space if the original machine is gone.
   You can do this on dropbox.com by going to Backups, selecting the external drive backup, and deleting it. This will immediately free the space.
   
   
2. If you want to keep the data
   There is a feature called "Copy to computer" backup. It creates a normal folder copy that you can edit freely. It requires enough free quota to complete the copy. Since your account is already over quota, the copy will not finish unless you temporarily upgrade or clear space first. After the copy completes, you can delete the original backup.
   
   

Given your current situation, the only actionable path without upgrading is to delete the entire external drive backup.

If you want to keep the data, the only way is to raise your quota by upgrading to a paid plan, after we will opt you into "Copy to computer" feature, you will then copy your Backup content to Dropbox and after that you can delete the original backup.

Let me know if you have questions and I can help walk you through the steps.