Plank flooring on stairs with big lip- what do I do?

[Case Collett]

Need some help, as I'm not sure exactly what to google. I am redoing my stairs that were previously carpet and putting on vinyl planks. I ordered stair nose BUT, it looks like a nose was built into the stairs and then carpeted over. How do I handle this lip? Do I fill in the void on the rise with a piece of wood? Do I knock that piece off of every stair? Any other options? (the pictures rotated 90 degrees, apologies)Thank you very much!

-Case

[Kurt F.]

Before you trim off the nosings:

The IRC has been adopted nationwide, with relatively few exceptions.  Check your city's website.  Here's the IRC text regarding nosing requirements:

49. PROFILE. Section R311.7.4.3 IRC 2009 The radius of curvature at the leading edge of the tread shall be no greater than 9/16 inch (14.3 mm). A nosing not less than 3/4 inch (19 mm) but not more than 1 1/4 inch (32 mm) shall be provided on stairways with solid risers. The greatest nosing projection shall not exceed the smallest nosing projection by more than 3/8 inch (9.5 mm) between two stories, including the nosing at the level of floors and landings. Beveling of nosing shall not exceed 1/2 inch (12.7 mm). Risers shall be vertical or sloped from the underside of the leading edge of the tread above at an angle not more than 30 (0.51 rad) degrees from the vertical. Open risers are permitted, provided that the opening between treads does not permit the passage of a 4-inch diameter (102 mm) sphere. Exceptions: 1. A nosing is not required where the tread depth is a minimum of 11 inches (279 mm). 2. The opening between adjacent treads is not limited on stairs with a total rise of 30 inches (762 mm) or less.