Leaven is an important symbol but it’s not a symbol of bread; it’s a symbol of spreading malice, hypocrisy, wickedness and false doctrine. We absolutely eliminate leaven from our homes after the Passover but God isn’t interested in crumbs. We eliminate leaven so we can avoid the sin of eating leavened products.  More importantly, our primary focus before the Passover is to eliminate the cause of sin in our lives.