how to reset all stored data store using shared preferences

I have created an activity where i have used shared preferences for storing data..now in another activity i have an reset button..when i click on the reset button the data store will be lost..so how that can be done..my code is

code in activity1:

    public void writeToRegister()
    {

            // Write history data to register
            SharedPreferences preferences1  = getPreferences(MODE_PRIVATE);
            SharedPreferences.Editor editor1  = preferences1.edit();
            editor1.putInt("iHistcount", CycleManager.getSingletonObject().iHistCount);
            for(int i=0;i< CycleManager.getSingletonObject().iHistCount;i++)
            {
                editor1.putLong("dtHistoryDate"+Integer.toString(i), CycleManager.getSingletonObject().dtHistory[i].getTime());

            }
            editor1.commit();
    }

    public void readFromRegister()
    {
            // Read history data from register
            SharedPreferences preferences1 = getPreferences(MODE_PRIVATE);
            CycleManager.getSingletonObject().iHistCount=preferences1.getInt("iHistcount", 0);
            for(int i=0;i< CycleManager.getSingletonObject().iHistCount;i++)
            {
                Long x=preferences1.getLong("dtHistoryDate"+Integer.toString(i), 0L);
                CycleManager.getSingletonObject().dtHistory[i]=new Date(x);
            }
    }

code for Activity 2:

Button pBtnReset = new Button(this); 
    pBtnNextMonth.setOnClickListener(pBtnReset OnClickListener);
    Button.OnClickListener pBtnReset OnClickListenernew Button.OnClickListener()
    {
                public void onClick(View arg0)
                {


                }
    };

so what i have to write in second activity reset button so that it clear the stored data