To stop receiving experimental updates, you can navigate to the Settings page in the Homey Developer Tools.
There, you can disable experimental updates.
Note: Homey will not downgrade when you disable experimental updates. Instead, it will wait for the next stable release with a higher version number than you current software, to then update to the stable channel.
Would you rather downgrade entirely to the latest stable software version right away? This is possible only by reverting Homey back to its factory defaults via a computer. Please note that this course of action will erase all the data on your Homey. This data will be completely lost, unless you still have a back-up available in your Homey+ account that was made on that lower software version.