Cut 45 degrees to the width of the door in the middle of the threshold.
You can knock out the two pieces with a hammer once it is cut.
It's best to buy a replacement threshold and cut it to length. Home
Depot has many to pick from. I typically buy oak and apply stain and
polyurethane (3 coats).

wrote:
I need to replace my door sill and threshold this weekend. I just
wanted to know if anybody else had done this and what is the easiest
way of getting the old door sill out. What is the best material to cut
a door sill out of?

All help is greatly appreciated.