How to remove sub menu

Please identify exactly which theme you are using and then post in that theme’s dedicated forum via its page so the theme’s developers and support community can help you with this.

I’m using Jupiter theme

You’re using a commercial theme. For commercial product support please contact the author directly on their site. We feel they are best equipped to support their products.

https://jupiter.artbees.net/

As the author is aware, commercial products are not supported in these forums.