How to really, really (really) delete selected songs from my iTunes library for good... as in, forever.

My iTunes library of over 20k songs is stored on an external drive that is hooked to my laptop (no Cloud for this guy). Only a few songs were purchased through iTunes Music Store. The lion's share were downloaded from CDs and the like.

Recently I was having iTunes font issues (songs/words not appearing in List mode), which turned out to be my Windows graphic driver defaulting to an old update that was incompatible with recent iTunes updates.

While troubleshooting, I completely uninstalled then reinstalled iTunes, multiple times. Unfortunately I ended up deleting the folder with my playlists too, but was able to import them from my smartphone.

When I reinstalled iTunes and pointed it to my external drive where my library is stored I was dismayed to find the many, many songs I had painstakingly evaluated and deleted from my library over the past few years, are now back in my iTunes library! I thought when I selected "Delete from Library" those thousands of songs would be gone for good.

Is there a way to really, really (really) delete selected songs from my iTunes library so they will never reappear again?