Write a code showing how one can change a default username or password mainly for ActiveMQ console.

The following code can help a user change a default username or password:

Change from

# Defines users that can access the web (console, demo, etc.)
# username: password [,rolename ...]
admin: admin, admin
user: user, user 

To

# Defines users that can access the web (console, demo, etc.)
# username: password [,rolename ...]
NewUserName: NewPassword, admin
user: user, user