Hi there,
Do you have an example of which pages use this mobile menu?
From the testing I did, I could not get the menu that uses that code.
It would be beneficial to ask your developers if this code is still in use
(I would describe it as: the drop down menu which has an ID of "yt-mobilemen")
If this menu is no longer in use I would remove it as it is affecting your keyword density and does not look very natural, which will not be seen positively by Google, due to it being part of a dropdown, there is no association of it being part of the navigation, so to Google it just looks like a big block of keywords.
The mobile menu I witnessed came in from the left, was very nice and uses the same code as the full size one so as not to cause duplications, this is the preferred method, so if you are able to get rid of the big block of text, then go for it!
Be aware that initially it will be seen as a block of text disappearing, so would be helpful to add some more substantial text to your pages to compensate
Kind Regards
Jimmy