CENTS OS PLESK Disk /dev/sda1 FULL DELETE SOME FILES !!!!

I wanted to download a remote ftp backup in plesk to download from my server and store on usb on trying to do this /dev/sda1 became full and i get the error Disk space usage has reached the specified threshold on host [login to view URL]: Device name: /dev/sda1 Mount point: / Capacity: 10403128 kilobytes Used disk space: 10403128 kilobytes Maximum number of files: 655360 Current number of files: 261213 I have deleted the backup from my plesk backups section but it has not deleted from disk partition. I would like it deleted the space cleared, as well as other space that can be cleard while you are there, and a fix so i can create backups locally and download them to my usb stick to prevent this happening again. Also i would if possible like a root ftp password and login configured. Also i have zabbix installed i would like it removed. As i have munin which needs updating to a new version.