To disable YouTube Shorts on desktop, open Settings, then General or Playback and performance, and turn off Show Shorts, or click Don't show Shorts…
The browser version gives you the cleanest result.
The YouTube app is where this gets messy.
Each approach trades effort against how thoroughly it removes Shorts.
Hiding the Shorts shelf removes the prominent block from your home page, but it doesn't wall Shorts off entirely.
Read the complete breakdown, fixes and what happens next.