That is a bit strange?
The preposition should probably be from, but you're missing around
... take the locket from around his neck.
Men don't often wear lockets.
The article should be the, not a, unless he happens to be wearing several lockets!
Oh, yes, and the locket would be on a chain. I don't think that matters, though.
Which preposition should better be used in this context?
to take a locket from/out of his neck