how can I disable avamar client ?

hello everyone;

I have couple avamar VM clients, they are not actives now. I don't want them to backup. I tried to remove them from Default Virtual Machine Group even I created new group " no active" to add them in but when I re-edit them, they still show Default Virtual Machine Group. and backup job keeps failing with error status "No VM" Anyone knows how to fix it ? Thank you.