We want to move a large number of customer portal users (users who self-register via a pre-existing Contact record) from one "User License" type to another. But I note that in the User edit page the "User License" field is not editable (whereas it is for other license types) and in any case as thousands of users are involved we would like to automate the process.
Can this be done via an Apex script? Or can this be done via a Salesforce support request?