bbPress.org

Using this plugin:

https://bbpress.org/plugins/topic/50

You can customise what appears under the user’s name.

Don’t worry about the first section of the plugin, just skip to the last field. Entering a single <br /> tag in that field will stop anything displaying.

Unfortunately the plugin can’t change “keymaster” to something else, for that you will need to hack or use a new language file as Detective suggests.