To downgrade from a higher software edition (pricing plan) to a lower one act as follows:
1. Check that your account does not exceed any limits of the chosen lower pricing plan. Limits are listed at /terms/#limits.
2. Disable all special features, which are provided by the higher edition. This can be done at Settings -> System settings -> Professional functions and/or Enterprise functions.
A special feature can be disabled if there is no special data that is created by that function. For example, to disable the functionality of the Serial numbers, all serial numbers should be deleted.
3. Go to Settings -> Account and Billing -> Profile, click Edit, then choose and save the edition/plan that you would like to downgrade to.
4. Check in Settings -> Account and Billing, that you have the desired pricing plan, and the next invoice amount is as expected.