If you’re using our native packages, then you just need to update the repository configuration to point to the stable repo instead of the nightly repo, and reinstall the package. If this is the case and you had installed using the kickstart script, you can easily do this by installing netdata-repo using your system package manager (this should uninstall netdata-repo-edge at the same time).
If you’re not using our native packages, then the most reliable way to change between the stable and nightly channels is to use the kickstart script to reinstall as outlined in our documentation.