The pre-release version of Nightfall and the "Official" version of Nightfall work independently from each other. You can choose to keep both, or delete the pre-release, it's up to you.The upgraded Nightfall will NOT replace the pre-release version in projects that already used the pre-release. If you want these projects to continue working as they are, you will need to keep the pre-release copy of Nightfall on your computer somewhere.We would recommend deleting the pre-release version of Nightfall once the newer version is installed, but be aware that you will need to manually replace any existing instances of Nightfall in older projects.