You can change your production's current script to a new file you've uploaded by doing the following:
Tap Documents icon in the upper left corner of the script to view all the files in your Binder.
Tap "Select" in the upper right corner and choose your file.
Tap "Connect to Scroll" in the upper right corner
Tap the green "Connect" button to confirm the change.
Once you've changed your current script, you can archive or delete any files you don't want to keep in the Binder.