I once heard that one movie star used to go into the mountains and scream for hours. First, Screaming will not lower your voice. DO NOT try this. In fact, screaming or yelling for prolonged periods of time can actually injure your vocal chords. If you've ever yelled a lot at a sporting event and experienced a sore throat the next day, you know what I mean.
All voices are beautiful when properly played.
And some voices are just naturally higher than others. But all of us have an optimal pitch. Your optimal pitch is the speaking range that's healthiest for your particular voice, the range within which you have the greatest amount of resonance, comfort and vocal flexibility. If you feel your voice is too high, you may be habitually speaking above your optimal pitch. And if this is the case, you can definitely change it.