In order to downgrade your Netcore account plan, please follow below steps,
1. Login to your Netcore account, URL: https://email.netcorecloud.com/
2. Go to the billing section.
3. Under ‘Your current Plan’ section, click ‘Change Plan’.
4. All the available plans will be shown. Choose the plan to which you want to downgrade. Here is the sample screenshot.
5. The changes will be reflected from the next billing cycle onwards.