The External Data window appears automatically after you have successfully linked shapes in your Visio drawing to an external data source such as Excel spreadsheet, Access database, SQL Server database, SharePoint list, an OLEDB or ODBC data source, to name a few.
Note: To display the External Data window, on the Data tab, select the checkbox next to External Data Window.
Unlink rows from shapes
In the External Data window, select the row or rows that you want to unlink.
Right-click any of the selected rows, and then click Unlink.
Unlink shapes from rows
In your drawing, select the shape or shapes that you want to unlink.
Right-click any of the selected shapes, point to Data, and then click Unlink from Row.