Transfer PowerBI Data to new user

Are you asking if you can assign permission to another user to have access to Power BI Dashboard? Power BI is a cloud-based service where data and the back-end engines are powered by set of Azure services. Data is not being owned by anyone.

If a user no longer works at the company, the user license is removed (from Office 365 portal) and he has no access to the Power BI dashboard or reporting. Nevertheless, if that user intends to download the database before leaving the company, he can if he has privilege to pull out data to his Power BI Desktop. Or if he is a DBA who has access to the data source which Power BI connects to, then data leakage is a concern.

Hope that addresses to your question.