This is probably controlled by your theme. What theme are you using? Where did you download it from?
I’m using HOWL. Based on my observation it looks like our mobile menu is hard-coded in the CSS of the child theme. I’m having a hard time identifying the codes and hiding the menus so that we can implement a plug-in.
We hired a web-developer and I’m struggling to understand what was created here.
I contacted my theme support team.
Thank you!