After verifying the steps provided in Verifying the Domain Leave, the domain leave still fails. This is because,
Domain Controller (DC) or DNS server is not working properly or
Netbios name of the OES host or cluster resource is modified after the OES host or cluster resource is joined to the AD domain.
To resolve this issue, perform the following:
Delete the computer objects in the AD domain manually.
Remove the /etc/krb5.keytab file.
In case of cluster resource, remove the /media/nss/VOL1/._NETWARE/vol.keytab file.
After completing these steps, the OES host and cluster resource are brought back to the state where it can be joined to the AD domain.