The answer to 'how to kill spider' is to use a spider-killing insecticide spray or gel. Apply the product directly to any spiders or webs you see, following the instructions on the label carefully. This will effectively kill the spiders. For best results, treat any areas where spiders are commonly seen, such as corners, cracks, and crevices.
It's important to take safety precautions when using insecticides. Wear gloves, open windows for ventilation, and keep children and pets away from the treated areas until the product has fully dried. Avoid spraying directly on plants or food preparation surfaces.