Changing your intention is permissible before giving it away. However, you must be sure it is someone who is poor or needy.

I intended to give a piece of gold of mine to one of my family member as charity. But now I am thinking to give it as my zakat to them. First I intended to give purely as charity not zakat. But now I want to give it as my zakat. Is it ok to change my intention from charity to zakat. Pls reply