The pure compound is disposed without treatment as a separate bottle.
With hydrogen peroxide hydrazine is instantaneously oxidised to nitrogen and water. The reaction will be violent if the mixture is not sufficiently diluted. Add the hydrogen peroxide until the evolution of gas subsides. More accurate is to check for the presence of free peroxide - for example with potassium iodide / acetic acid (See "Organikum"). When the reaction is finished the mixture may be flushed down the drain. A little excess of peroxide is no bigger problem than the oxidising suds of your washing machine at home. All equipment which has got contact with the hydrazine may also be decontaminated with diluted peroxide.