I don;t believe you can "downgrade" within Windows itself, but you can reinstall your OS, installing the Home variant.
Ensure you back up your data beforehand, and you can create install media here:
https://www.microsoft.com/en-ca/software-download/windows10
bicycle_repair_man :
Assuming you have a valid product key and you aren't changing architectures (32-bit and 64-bit) then you can downgrade by opening Settings > System > About.
IIRC, you can only "upgrade" via that route, not "downgrade". I could well be wrong OP, so double-check.