Why did George and Lennie leave Weed?

George and Lennie left weed because Lennie was accused of sexual assault

Lennie Small grabbed a woman's red dress but didn't let go and had been accused of sexual assault by the woman so they left town. Lennie still hadn't let go but, then George came around and heard the woman screaming only to see that it was Lennie causing trouble. George hit Lennie over the head with a hand-tool so he'd would let go of her then they ran away.