To rename a project folder, first select the folder name you want to rename then:

 

 From the menu select Project -> Rename

or

 Right-click and then select Rename

 

The following window will then open:

 

 

 

Enter the new name you want to use for your folder and then Click on OK to save your change.  The window will then close and you will see that the folder name has been updated with the new name.