I am very sorry but deleting the keyfile did not help, since the cyberpanel itself had a root RCE vulnerability and they came back and injected an encryption virus. All is gone/encrypted.
You can check here for information.
Can you tell us how you deleted the hackers ssh keys and stopped the attack in detail. Will be useful for others.
I have removed the key from the authorized_keys file, but as described above, this did not help.
Best is to block any access to port 8090 and 7080.
