Hiding Semantic Models (datasets) in a workspace

You can't move them, you just publish them again to a differen't Workspace and then re-point your reports towards it.  It's not that big of a deal if you have a reasonable # of reports to update, but if you have anyone using the Excel connection, it will break it.

Once you publish your Dataset to a different workspace, open your reports in Desktop.  Click "Transform Data" > "Data Source Settings" and select the Dataset from it's new home.  Publish the report, repeat for each report.