Jess Mann

This plugin adds an additional admin page which shows you every registered 
widget, and allows you to deactivate any you do not want to appear. For 
example, when you are adding widgets to a sidebar, the Post Loop widget is 
usually not wanted, and just adds additional clutter you must sort through. On 
this widget’s admin page, simply click on the widgets you would like to 
disable, and then hit the “Save” button at the very bottom of the page!

Customize Widgets

Too many widgets cluttering up your wordpress install? This plugin allows you to hide unwanted widgets from the Appearance > Widgets panel, and any …

Ravi

This plugin is for WordPress developers working with clients and for people who want minimalism in WordPress admin. It hides unwanted or least used menus from WordPress admin to reduce clutter. For example, if you don’t want your client to play with WordPress settings, change theme or add plugins you can hide them. If you don’t use tools or users or links menu often you can hide them.
The hidden menus can be viewed again by deactivating the plugin and each menu item is visible by directly visiting the URL. So, there is no risk and yet it is not completely tamper proof for the clients. The main idea is to reduce clutter in WordPress admin and it be used for this purpose only.
There are white label CMS plugins and user role plugins which offer similar features but this is a simple plugin that just does one thing well.

Simple Admin Menus

Hides unwanted or least used menus from WordPress admin to reduce clutter.

Customize Widgets vs Simple Admin Menus