Notes for removing windows
After the trim ring is off with the flex blade putty knife under flange and cut along and even may need to use a hammer to cut through on the outside of the window.
Round corner of putty knife
Puss out at times
Use a razor knife and push out at times
Use a sharp chisel and clean out side surface well
Use 240 sand paper and scotch bright etc
Use Acetone then denatured alcohol
Put on little finger size bead of sealing compound
Put in two screws at top and bring in with screw driver, do not push window in.