By default operators does not have permission to delete his own chats. You grant them permission to delete his own chats by assigning.
"Allow user to delete his own chats" this function to operators role (deletechat).
After you update role. Operator have to logout and login again.
Developing application takes a lot of time. You can support application by donating. There is no company behind this application and it takes away my free time. Every donation matters and does not matter how small it is!