Organizing Using Statements
The Organize Usings options in the Visual Studio integrated development environment (IDE) provide an easy way to sort and remove using and extern declarations without changing the behavior of the source code. Over time, source files may become bloated and difficult to read because of unnecessary and unorganized using directives. The Organize Usings options compact source code by removing unused using directives and improves readability by sorting them.
To see the available options in the Visual Studio IDE, on the Edit menu, point to IntelliSense, and then point to Organize Usings. The IDE provides the following options to organize and remove usings statements:
Remove Unused Usings
For more information, see Removing Unused Usings.
For more information, see Sort Usings.
Remove and Sort.
using Directive (C# Reference)