Hi Balaji,
If you are talking about the database users, those you configure via configuration tool, you can:
- Create new users and drop those you have at the moment. Then update the configuration to use the new users instead;
- You can change the password via database (Oracle and MySQL examples). Then you just have to update the configuration;
For application users, you can follow this KB article. Only valid for on-premise environments. For your Personal Environment you need to contact OS support.
IG