To remove a principal from an existing keytab, use the kadmin
ktremove command.  The syntax is:
     ktremove [-k[eytab] keytab] [-q] principal [kvno | all | old]
     
The ktremove command takes the following switches:
     
ktremove will use
the default keytab file (/etc/krb5.keytab).
     ktremove to display less verbose
information.
     For example:
     kadmin: ktremove -k /usr/local/var/krb5kdc/kadmind.keytab kadmin/admin
     kadmin: Entry for principal kadmin/admin with kvno 3 removed
          from keytab WRFILE:/usr/local/var/krb5kdc/kadmind.keytab.
     kadmin: