Stairs help

Draw a fence around any area where you want to delete the floor tiles. Use the hammer to delete the floor, then use the hammer to delete individual fence pieces. If the floor reappears, just click it and delete it.

@Mstybl95 Thank you! I will give this a shot.

@Mstybl95 Ok, that got me far enough that I was able to make a fix on my own! I did as you suggested, but deleting the floor the second time caused the floor to disappear in the adjacent room as well-- the floor of the second-story outdoor walkway, on the other side of the wall from the room with the stairs. Here's my fix, just in case anyone else has this particular problem, I know a lot of people struggle when building with stairs. (There were also a few other oddities I ran into that others might find interesting or have seen before? I don't build much and always happy to learn something.)

Fences in place on second floor
https://i.ibb.co/fnxyn9T/06-02-21-3-58-40-PM.png

I had to draw a fence on the first floor as well. This runs directly underneath and parallel to the second-floor wall with all the windows separating the stairs room from the outdoor walkway.
https://i.ibb.co/QmNCd7P/06-02-21-4-07-52-PM.png

The fence happens to run directly across the bottom of the lowest staircase. Note that the stairs have now been cut in half and are floating in midair.
https://i.ibb.co/fGD4Wws/06-02-21-4-08-21-PM.png
https://i.ibb.co/F6Sd1gK/06-02-21-4-08-26-PM.png

Deleted one section of flooring, all is well.
https://i.ibb.co/wwMMrSZ/06-02-21-4-07-56-PM.png

Removed fence, deleted next section of flooring, all is well.
https://i.ibb.co/VL47KMK/06-02-21-4-09-05-PM.png

Removed fence, one section of flooring came back.
https://i.ibb.co/wKCycJ6/06-02-21-4-09-15-PM.png

Deleted that section of flooring. Outdoor walkway flooring in the next room remains intact.
https://i.ibb.co/zHLGRQx/06-02-21-4-09-24-PM.png

But the lowest staircase disappeared completely. (The first-floor fence remained; I removed it manually before I took the screenshot.)
https://i.ibb.co/zR1XN5s/06-02-21-4-10-06-PM.png

I built another staircase. Oddly, it is in exactly the same place as the old one, same height, but it extends one tile less far into the room. It must be a bit steeper than the old staircase.
https://i.ibb.co/XpNjkKz/06-02-21-4-10-29-PM.png

I don't really mind that so much, but it did make me wonder, have I stumbled upon some complicated way to adjust the slope of stairs?? (steepness/shallowness)

I also wish I could delete those back stair rails that are drawn on the wall, or the weird floating lines above the stairs, but I think this will have to be good enough. Moving on with life.
https://i.ibb.co/Nmzk4MG/06-02-21-4-12-29-PM.png
https://i.ibb.co/9318QSp/06-02-21-4-12-43-PM.png

Great tutorial! Thanks for sharing.