I was taking some interval photos from the inside the building to record the sunrise. I get the sun reflection and glare in the window. Do you have any suggestions how to eliminate that (polarizing filter for the camera or something similar)?

Glass reflections are going to be an issue in many setups. Polarizers might help... worth a try! Fundamentally though, it's a tough problem. Minimize the distance from the lens to the window, use black felt to mask areas around the lens, etc. Clean the windows as much as possible, try to shade the sun from striking the glass in front of the lens...