We need to remember that Word isn’t an image editor and its ability to edit images is somewhat limited as it lacks the tools.
Click the image to see your flange image with the background being removed using the Mark Areas to Keep option.
It is a low quality image and the result is as expected - poor.
Because of the low quality, using the ‘Mark Areas to Keep’ tool allows spotting with the mouse to select the wanted area(s). Higher quality images need the tool to be drawn across an area that’s wanted.