unharness

verb (used with object)

1. to strip of harness; detach the harness from (a horse, mule, etc.).
2. to divest of armor, as a knight or warhorse.

verb (tr)

1. to remove the harness from (a horse, etc)
2. archaic to remove the armour from

v.mid-15c., “divest of armor,” from un- (2) + harness (v.). Cf. Dutch ontharnassen “to disarm.” Meaning “to free (a horse) from harness” is recorded from 1610s. Related: Unharnessed; unharnessing.