The password it is asking for is the database's root password, which is the one you obtained from the launchpad or deployment manager. It can also be found at
~bitnami/bitnami_credentials. Please check this for more information.
As a summary, the command you need to run is:
mysql -u root -p bitnami_wordpress -e "UPDATE wp_users SET user_pass=MD5('NEWPASSWORD') WHERE ID='1';"
Where NEWPASSWORD is the password you want to use in the application, but when it prompts for the password, you should insert the current one.