I am planning to replacement my basement windows (see this related question) and was planning to remove both the glass and frame. A window vendor advised me not do this claiming that the steel frame is supporting the concrete and removing it could cause the foundation to crack. They recommended that I re-use the frame (which is in bad condition on the outside). I would prefer to remove the steel frame since in its current condition, I don't think it is able to keep the water out. I suppose I could try and repair the frame (bang it back into place, use an abrasive brush to remove rust, re-paint and caulk all seams) instead.
Is foundation cracking a realistic risk and are there any other risks in removing it to warrant keeping it instead?