Honestly, it will be faster for you to copy the path in Illustrator, do your edits, and copy it back in Xd 🙂
Xd is quite limited in it's path editing abilities. You can only break a path at the first/last point, and you can only delete the last segment of a path. You can't select a point and cut the path wherever you want to.
If you just select the path (without going in to edit it) and then switch to the pen tool, you will see the point where you can cut it.