Step firmly onto an upright can, using your body weight to crush the empty can. If the can will not readily crush under your weight, stomp downward on the can to add force. Don heavy footwear to attempt this method of crushing, as a poorly aimed blow may only partially crush a can. As there is a danger of injuring your foot, you may want to try an alternate method.
Lay a can on its side on the ground. Step gently into the middle of the can, forcing the ends to partially fold inward. Step on each end individually to force it to fold the rest of the way, creating a flattened can.
Bring a heavy hammer or other weight down onto the can from above. Using a sledgehammer, swing the hammer down onto a can to crush it, or grasp the handle to lower the head of the hammer onto the can. The latter method offers greater control and less likelihood the can will slip or fly out from under the blow.
Acquire a can crusher. The device mounts on your wall and operates manually. Insert an empty can into the device, then lower the crusher's handle to deliver the force needed to crush your can. This method can be time-consuming, as you must add and retrieve each can from the crusher unless you obtain a version capable of holding numerous cans. These mechanisms can crush a can to 1 inch or less in height.
Use a motor-powered can crusher to quickly process a large number of cans. Devices are available to handle regular-size and tall cans and to operate with minimal noise, so they are suitable for use in food and beverage service businesses.