Leaving the domain before attempting to join a new domain or changing a computer name ensures that there will not be file conflicts or orphaned information that might prevent the join operation from completing.
You should note that leaving the domain removes all of the Centrify-specific information for the managed computer from Active Directory and reverts any computer settings that were changed by the adjoin command to their pre‑adjoin condition. These changes include reverting PAM, NSS, and Kerberos configuration files to their pre-adjoin states and deleting the /etc/krb5.keytab file. Leaving the domain does not delete the Active Directory computer object itself.
Leaving the domain does not delete the Active Directory computer object itself. If you want to completely remove any record of the computer from Active Directory, you must delete the computer object using Active Directory Users and Computers.