Solid Hardwood, Engineered and Laminate Flooring - stair nosing in door jamb

I want to install stair nosing in a door opening (door has been permanently removed) that leads to a small step down. I need to cut back the ends of five or so planks (bamboo) by about three inches that run up to the step down in order to leave a clean line so that I can install the stair nosing against the line of plank ends. I'm thinking of using a circular saw (adjusting it so that I don't cut into the subfloor), but the saw's housing doesn't let me get right up to the door jamb - I'll be left with about an inch of uncut plank on either side. Any suggestions how I might finish the cut?

You need a Fein tool

Or is it Fien tool?

Do a web search.

It looks like an angle grinder. But has a saw tooth spltula, that ocilates, instead of spinning.

Lacking a Fein tool, I make the cut with the circular saw, then finish the last unreachable parts with a reciprocating saw. You must be careful though to not let it bounce around.

We just use a GOOD SHARP chisel. The fein tool costs several hundred dollars and the reciprocating saw is a gamble. You can buy an excellent chisel for thirty bucks and you'll be fine.
Good Luck
Bryan

Ditto the chisel! Mark your line and make you first strikes along it softly to establish the cut. Then pound away moving along the line. I like a smaller size such as a 1/2" or 3/8". More force per sq inch. Stanley costs under $15. Sometimes these guys need to remember how things were done in simple ways.....

Or score it several times with a razor knife before your wack it with a chisel.