Stop OpenDJ service
bin/stop-ds
Generate an encoded password for Directory Manager
bin/encode-password -s SSHA512 -c MyN3wPa88w0rd Encoded Password: "{SSHA512}BmU5JuOZW6c0ngGetV1J8EG5UgWqyS5k/2JoJEEnx/V/c6EbnXvFwyLFG7ZWZm3oAwCmlht28OYnwQK+X8yLMV+dZJ3cBvOd"
Edif the config/config.ldif file and replace userpassword.
dn: cn=Directory Manager,cn=Root DNs,cn=config objectClass: person objectClass: organizationalPerson objectClass: inetOrgPerson objectClass: top objectClass: ds-cfg-root-dn-user userpassword: {SSHA512}BmU5JuOZW6c0ngGetV1J8EG5UgWqyS5k/2JoJEEnx/V/c6EbnXvFwyLFG7ZWZm3oAwCmlht28OYnwQK+X8yLMV+dZJ3cBvOd
Start OpenDJ service
bin/start-ds
Tribute to Ludovic Poitou https://ludopoitou.com/2011/06/30/newbie-help-how-to-reset-the-directory-managers-password/