DB2 does not store user authentication credentials, but uses external systems for authentication - DB2 For Linux, Unix, Windows (LUW) by default uses underlying OS for auth.
If you have Linux installation, SSH to machine and check if "db2inst1" user exists in OS. If so, just change its password (sudo passwd db2inst
) in OS shell. Of course this is only default user name, your actual may differ (but on Linux it will be the same as DB2 instance name, hence the warning of scanner).
The "use underlying OS for authentication" is default on Windows machine as well, but db2 sysadmin user name may differ from instance name.