While it is possible to downgrade from Business or Home edition to the Community edition, it is recommended that you reinstall ClearOS.
Why? Apps like “Master/Slave”, “Performance Tuning”, and others are baked into the system. You can't downgrade these items without quite a bit of hacking. Examples include:
There really isn't a realistic, practical way to downgrade without reinstalling ClearOS. If you need to migrate configuration settings, you can download the configuration backup file and manually read it. Then you can take that info and manually configure using that information. An example would be extensive firewall rules.
ClearOS will still work but no updates will be received. It is recommended that you purchase a Business subscription or reinstall ClearOS under the Community edition to continue to receive updates.