Hi @albert-a
I am sorry to hear about this terrible issue.
Passbolt does not offer revocation certs yet.
https://help.passbolt.com/faq/security/revocation-certificate
If you know your ip address you can block the address.
You can delete the user
https://help.passbolt.com/api/users/delete
Looks like the disable user feature is still in the pipeline.
https://community.passbolt.com/t/as-an-administrator-i-can-disable-users/7980/2