1. Open the project’s root folder.
2. In Windows Explorer, right-click on project’s Main solution (.sln) → “Rename”.
   
3. Open the project in Visual Basic. In “Solution Explorer”, right-click on project → “Rename”.
   
4. In “Solution Explorer”, right-click on project → “Properties” → goto “Application” tab, rename “Assembly name” and “Default namespace” to match the project’s name.
   
5. If you wish to also rename the namespace, open one of your class files. Right click the namespace →”Rename…. ” This should search and replace all references to your namespace throughout the project.
6. Close the project. Delete the old “Solution User Option” (.suo).
   
7. In Windows Explorer, right-click on project’s subfolder → “Rename”.
   
8. Edit the .sln file and change the path of “.vbproj”.
   

Source: https://stackoverflow.com/questions/211241/how-can-i-rename-a-project-folder-from-within-visual-studio