1 : to dismiss from employment <the firm let him go at the end of the month>
2 : to abandon self-restraint : let fly <spoke in clipped sentences, as if fearful of letting go ― David Kline> <there just to party, just to let go ― Philippe Vergne>
3 : to relax or release one's hold ― used with of < let go of stress ― Kathy McCoy> < let go of my arm>
4 : to fail to take care of : NEGLECT < let himself go and got real fat ― Bill Parcells>