Edit Queries grayed out - How can I view the source data in Excel and append data to this source?

[olimits7]

I still have access to an intern's account who no longer works here. He created a report in "Service" under his "personal workspace" so there isn't an option to download the *.pbix file. So I ended up going to "Desktop" and I was able to select the same dataset he used in "Service" and I recreated the reports and published them to a "group workspace"; so I can edit the reports in the future and we can delete his account.

My issue is how do I update data in this dataset? I can't go under "Edit Queries" in "Desktop" because it's grayed out. If I click on "Refresh" it looks like it refreshes properly but I have no idea where the source file is that it's refreshing from.

I tried going back into "Service" under "Settings > Datasets" and when I click on that dataset all I see is the following.

Refresh can't be scheduled because the data set doesn't contain any data model connections, or is a worksheet or linked table. To schedule refresh, the data must be loaded into the data model.

Parameters haven't been defined for this dataset yet. If you want to set parameters, use the Query Editor.

Why is it so difficult to just get to the actual source data so I can continue to update it with new data?

If my company deletes this intern's Microsoft account, will this dataset also get deleted and not work with the new "group workspace" report I just created?

Thank you!