Hello.
At this time, you do not qualify for a disk space upgrade -- the vast majority of your space is used by a directory named "softaculous_backups" and a file "public_html/restore"
The first contains backups which you should download to your computer and then delete off the server (storing backups onsite doesn't make much sense anyway, as if something were to happen to your account you'd lose access to the backups). I'm not sure what the second file is for, so if you could shed more light on that I would appreciate it.