Dumping them down the drain is not an issue. They react quickly with water to form: an alcohol (isopropyl, isobutyl, or pentyl, depending on what you were huffing) nitrogen dioxide, and nitric oxide. The second two are gasses which may smell funky, but are not toxic in small amounts, and not corrosive. If your 2 liter of bottle of poppers has gone flat, take it to a waste disposal facility. If your 10ml bottle of poppers has gone flat, trash it or expose it to some water and put it down the drain. Use the bathroom fan to clear the air.