un- + burden

source: [ワンパンマン 大荷物を下ろすジェノス｜無料GIF画像検索 GIFMAGAZINE 3981278]

verb with object

relieve (someone) of a burden.

【荷などを】〈人〉から降ろす «of»

relieve (someone) of something that is causing anxiety or distress:

〖～ oneself〗 «人に/…のことで» 胸の内を打ち明ける «to/of»

e.g. the need to unburden yourself to someone who will listen.