Proton offers different plans and the possibility to switch between plans whenever you wish to.
If you would like to downgrade your subscription, please first make sure that your account matches the features of the new plan. For example, you need to confirm that you are using the right amount of addresses, filters, or storage space, similar to those included in the plan you wish to switch to.
To check your storage space, go to your Dashboard in Settings. You will find a summary of your used features in the Overview section.
If you are using Proton’s V4 version, you can find this information in your Proton Account Subscription section.
If you are trying to downgrade your subscription without adjusting your account to the plan, you will get an error message prompting you to take the necessary steps.
To free up space, try deleting older messages that you no longer need or those with large attachments. To see the messages that take up large storage space, rank your emails by size: Large to small.
If you are the admin of an organization, you have to edit the storage available to the users who are members of your organization and reduce their number accordingly. For example, if you are downgrading from a Visionary plan to a Plus plan, your organization can have a maximum of 1 user and only 1 connected custom domain.