Right-click the shape and select Format Picture from the context menu. A Picture Format dialog box will appear. On the Picture tab, under Transparency, drag the Transparency slider or click the ...

One of the most interesting and lesser-known features of this tool is the Transparent ... from the background. Hold down the left mouse button and slowly trace around the image. A black outline ...

you can remove the area surrounding your selection and replace it with a transparent background. Which selection tool to use depends upon the shape of the object you want to select. For example ...