Pieter Bos

Whilst many people have opposed the decision, the navigation menu interface was forced into the Customizer.
As there are many people who don’t have to time to explain this to all existing clients, this plugin simply removes the menu panel/section from the Customizer.
We support this plugin exclusively through <a href="https://github.com/senlin/so-customizer-hide-menu/issues" rel="nofollow ugc">Github</a>. Therefore, if you have any questions, need help and/or want to make a feature request, please open an issue over at Github. You can also browse through open and closed issues to find what you are looking for and perhaps even help others.
If you like the Customizer Hide Menu plugin, please consider leaving a <a href="https://wordpress.org/support/view/plugin-reviews/so-customizer-hide-menu#postform" rel="ugc">review</a> or making a <a href="https://so-wp.com/donations" rel="nofollow ugc">donation</a>. Thanks!
<a href="https://so-wp.com/plugin/customizer-hide-menu" rel="nofollow ugc">Customizer Hide Menu plugin</a> by SO WP.

Customizer Hide Menu

Removes the Navigation Menu paqnel from the Customizer.

alpipego

This plugin makes long and complex navigation menus better manageable by creating groups that can be expanded and collapsed.
By default, all navigation menus in wp-admin will be collapsed. When holding the Option/Alt-key while clicking, all sublevels will be expanded with one click.
For general support, please use the support forums on <a href="https://wordpress.org/support/plugin/wield-menu" rel="ugc">wordpress.org</a> 
For developers: Head over to the <a href="https://github.com/alpipego/wield-menu/" rel="nofollow ugc">Github repository</a> 
For everything else, find me on <a href="https://twitter.com/alpipego" rel="nofollow ugc">twitter</a> or slack

Wield Menu

I had this problem when working on themes demo as they have all possible page in the menu.

Thanks!

Very handy

Make long and complex Navigation Menus wieldable

Customizer Hide Menu vs Wield Menu