I guess you could excavate the wood posts if you didn't want to saw the vinyl. Typically vinyl fence posts don't need wood supports, they are just cemented into the ground and left hollow. The wood can rot as water accumulates within the post.
Fence posts come in may shapes and sizes from a round metal chain link fence to a square 5 inch by 5 inch vinyl fence post. Vinyl fences can easily be repaired without the need to dig them up or remove them from the cement.
Installing vinyl fence slides over wooden posts has several advantages. The slides are hollow vinyl and are about 1/3 the price of solid vinyl posts. This method of fencing also saves money because you have no need for treated wooden posts due to the slide and cap, which will protect wooden posts from weathering, rotting and pests.
When you have fitted the rail hangers to the fence posts, slide the panels into the brackets and use screws to join the panels to the hangers. Install the accessories, use vinyl glue to fit the top to the posts.
In this project, we installed a simple board fence. This style allows those sitting inside the patio area to see a seamless, vertical look. At one of the fence post corners, fix the first board. Use a plumb level to ensure the board is vertical and nail it into place. At another fence post corner, fix another board into place.