The method provided by Daniiel Maslyuk,
https://xxlbi.com/blog/switching-from-imported-data-to-directquery-or-live-connection-in-power-bi/ Is definately the best option in my opinion. It relies on the data model being identical but the use case is normally this. 1. You have created a report in desktop, imported all the datasets, added measures, schema etc and published to the service. 2. You have started building additional reports in direct query using this same dataset 3. You now want to decouple the reports from the dataset or you wish to split an unweildy report with lots of pages into sdperate reports. In this case, there will be no differences betwen the imported dataset and the one in the service. As long as you delete all the queries in your report, save and reopen you willl be able to chose Power BI as the data source. Remember though that its not just M queries but any DAX table (e.g. dates tables, summarized) that need to be removed.
