Can a lvl 4 druid break charm person by imitating the actual caster and slapping the person affected?Or is there an ownership of the spell itself in which only the caster himself can cause it to be broken.

— Grumpy SQiRL (@GrumpySqirl) October 10, 2017

RAW, I don't believe it works, but as a DM I'd allow druid to make a Charisma (Deception) check with DC equal to spell save DC

— Mike Mearls (@mikemearls) October 11, 2017