Thanks for the response.
No, there is no conflict between the different menu types. What I want is to do the styling (CSS) only for Mega Menu. Then, somehow, I need to disable the other three menu type like they do not exist. For example when somebody login to the admin panel and go to Template Manager -> Profiles and when he expands the drop down for “Menu System” to see only one choice – Mega Menu. I tried to search in the php files to delete some lines but I could not figure it out.
Could you please guide me how I can remove these menu types like they do not exist? Thanks!