Just an update to this the new link is here:
https://docs.sonarqube.org/latest/instance-administration/security/#header-3
As it says on the link you can do this:
In case you lost the admin password of your SonarQube instance, you can reset it by executing the following query:
PostgreSQL and Microsoft SQL Server
update users set crypted_password='100000$t2h8AtNs1AlCHuLobDjHQTn9XppwTIx88UjqUm4s8RsfTuXQHSd/fpFexAnewwPsO6jGFQUv/24DnO55hY6Xew==', salt="k9x9eN127/3e/hf38iNiKwVfaVk=", hash_method='PBKDF2', reset_password='true', user_local="true" where login='admin';
Oracle
update users set crypted_password='100000$t2h8AtNs1AlCHuLobDjHQTn9XppwTIx88UjqUm4s8RsfTuXQHSd/fpFexAnewwPsO6jGFQUv/24DnO55hY6Xew==', salt="k9x9eN127/3e/hf38iNiKwVfaVk=", hash_method='PBKDF2', reset_password=1, user_local=1 where login='admin';
This will reset the password for admin user to admin.