During its lifetime, kube-cert-manager will create secrets to store TLS certificates. Each secret may be owned by zero or one Certificate resource and used by zero or more Ingresses. When kube-cert-manager detects that a secret it created is no longer needed, that is no Certificate resource and no Ingress reference it anymore, it will be deleted.
Garbage collection is a periodic operation. This means that there may be a delay between deleting a resource and the secret being deleted. In practice, this should not cause any problems. Reusing the secret name in a Certificate resource or Ingress will work correctly. If you wish to reuse the secret name yourself, you can manually delete the secret first.
The interval at which garbage collection runs is controlled by the
sync-interval command line flag.