let go vs let go of

let go and let go of both are verbs.

Word	Noun	Adjective	Verb	Adverb
let go	No	No	Yes	No
let go of	No	No	Yes	No

As verbs, let go and let go of are synonyms defined as:

Other synonyms of let go include release, relinquish.

let go (verb)	let go of (verb)
release, as from one's grip	release, as from one's grip
be relaxed