You can use masking (e.g. via the cookie cutter, or the masking part in pan/crop) to cut out the shadow area.
On a track below, put your replacement of the background in there. Three choices:
a- get a clean still of the background and stick that in. This will keep the texture of the wall. Do this if the camera doesn't move.
b- you may be able to use color correction to get rid of the shadows. e.g. use unsharp mask with a large radius and NEGATIVE amount.
c- white media generator.