Depending on environment and installation type you need to look for a file named auth under directory dbms and remove it.
In MacOs, for dmg installations (adjust for custom locations):
/Users/xyz/Documents/Neo4j/default.graphdb/dbms/auth
or (homebrew install)
/usr/local/Cellar/neo4j/x.x.x/libexec/data/dbms/auth
Windows users should look for same file in the default.graphdb/dbms directory.
In Ubuntu
/var/lib/neo4j/data/dbms/auth
In docker containers
/var/lib/neo4j/data/dbms/auth
Alternatively, you might choose to disable auth in the configuration file, usually found in
MacOs:
/Users/xyz/Documents/Neo4j/.neo4j.conf
or
/usr/local/Cellar/neo4j/x.x.x/libexec/conf
and set this property to false
dbms.security.auth_enabled=false
After doing this, you need to restart the server for changes to make effect, you will be asked for a new password.