To Edit Folder follow these steps:
If you are using mouse, right click on folder to edit.
If you are using touch device, perform select item gesture on folder to edit. (see below how to select folder using touch)
Folder will be selected and bottom app bar will be shown.
Tap on Edit icon.
Folder will be opened in edit mode.
Make changes and tap on save button.
How to select folder item using touch.
Touch the folder with your finger (Do not leave the finger from screen yet).
Swipe the folder item down slowly until check mark is completely shown just above the folder item.
Folder item will be selected and App bar will be opened from bottom.