You may be able to reuse the old siding if it is not damaged otherwise you may need to cut new sections.
How to replace a window in vinyl siding.
Do not cut the vinyl off.
Use a siding removal tool.
If you are replacing windows on your vinyl sided home and the old window frame sill and jambs are not damaged or rotted you won t need to disturb the exterior siding.
Step 1 measure the old window for dimensions for the replacement window using a tape measure.
Use this tool by inserting it where a piece of vinyl overlaps a piece below it and then sliding it across until you reach the end of.
Remove the pieces of vinyl siding from around the window area.
The easiest way to replace windows in a home with vinyl siding is to do the job from the interior.
With the window installed the last thing you will need to do to the exterior of the window is to replace any removed vinyl siding.
Measure the window width from jamb to jamb at the top of the window.
Extract nails keeping the vinyl pieces in place in order to prepare vinyl pieces to be removed.