You should be able to "scrap" settlers in workshop mode. You'd get:
-Their gear & loot
-Skull (50%) or Upper Skull & Human Jaw (50%)
-Complete skeleton (all skeleton junk bits except skull, upper skull & jaw, 30% chance of recieving "broken" variant)
-5 to 7 Blood Pack (irradiated blood if a ghoul)
Most companions or nearby name-bearing NPCs would "hate" this (some might like it), and the settlement's happiness would drop by 10 to 25%.
Anyway, I'm off to get me head examined, toodles!