Delete comments for guests per the user name
I would like to automatically be able to delete comments of guests based on the user name
Will this add on do it or do I need another add on?
Deleting comments based on a Username is not related to wpForo or wpForo addons. Comments and users are WordPress core components. You can ask this question in WordPress support forum and search for some plugin there. There should be many WordPress plugins to manage comments and users data. If you didn't find it, you should ask some developer to write a custom plugin for you. I'm sorry but we don't have such service.
WordPress has the "Comment Blacklist" textarea located in the Dashboard > Settings > Discussion admin page.