How to connect USB Charger outlet
Use a volt meter to find out which of the two hots is switched and which is not.

Use a wire nut to cap the one you don't want to use, and push it back into the box.

Install the usb outlet per its instructions.  If you don't have a ground wire to connect to it, hopefully the outlet box itself is metal and grounded.  If not, then you probably don't need to worry about grounding the usb outlet.