Tying

A rope or string you touch, knots or unknots itself from a hook, branch, or single protrusion within reach. (For example, an arm. This cantrip wouldn't knot two wrists together.)

If the cord is being held by another creature, this cantrip has no effect.

Your spellcasting Save DC becomes the DC for an attempt to untie the knot with an Intelligence (Sleight of Hand) check or to slip out of it with a Dexterity (Acrobatics) check.