How do i get rid of two lines on Mobile Burger but keep the x when you open the menu

Site URL: https://www.tuscanseagrillbar.com/

I currently have a custom image as my burger icon but when i open the menu, I would like to have the x in the top right so you can click out but without the two lines showing up when your out of the menu

Thanks!

I don't see them in mobile view except for just a half second then your custom burger pops in. I would never have noticed without knowing to look.