This is the topic tags. If you want to disable topic tags then it'll be disabled from everywhere, even from topic form editor, so you'll not use topic tags. The option is located in the Dashboard > Forums > Settings > Topics & Posts Tab. It's called "Enable Topic Tags".

As an alternative you can hide that bar using CSS code, this will also hide Topic Viewers and Related topics, all these data are located in that bar:

#wpforo #wpforo-wrap .wpforo-topic-footer{
        display:none;
}

How can I remove the bottom bar? Please see attached picture.

Thanks