This will work for X based installations, and not just for the Del key. KDE/Gnome usually have tools to remap a fixed set of keys to escape (e.g., Caps Lock), but I could not find a setting in KDE for Del -> Esc.

First, use xev to figure out what the hex keySym is for your Del key. In my case it showed 0xffff, but turned out that was not it. I did:

$ xmodmap -pk |grep -i delete
91         0xff9f (KP_Delete)      0xffae (KP_Decimal)     0xff9f (KP_Delete)      0xffae (KP_Decimal)

And used 0xff9f as the keySym code. The remapping is easy:

$ xmodmap -e "keysym 0xff9f = Escape"

After testing it works, best to stick it in your ~/.profile.

If you use VS Code, if a bug with remapped keys on Code running on X hasn’t been resolved yet, you will want to add:

"keyboard.dispatch": "keyCode"

to your settings.json.