how to change namespace in visual studio 2019 code example

Example 1: visual studio rename namespace

How-to
Place your cursor in the namespace name.

Press Ctrl+. to trigger the Quick Actions and Refactorings menu.

Select Change namespace to <folder name>.



See also

Example 2: how to manage namespaces in visual studio

Just right click on the name you want to change 
(this could be namespace or whatever else) 
and select Refactor->Rename... Enter new name, 
leave location as [Global Namespace], 
check preview if you want and you're done! 
write MyName in Assembly name and Default namespace textbox, then save