I think it really depends on how severe your phobia is. I can definitely give you some tips that might help you, but keep it in the back of your mind that you might need professional help with this if you're really not able to overcome your fears.
Firstly, it's very important that you know your topic. Practice, practice & practice some more! Make sure that you read your text out loud in front of a mirror or a small audience of friends and/or family. Get more adept at speaking that way, it also helps to record yourself.
It's important that you're able to tackle any nervousness when you're finally giving your talk in public. There are some breathing exercises that you can look up, they might help you out in the moment. Believe in yourself, if you know your topic, that's already less reason to be nervous.
If these things fail, you can join a training course for public speaking. There are probably classes for that where you live, it's not that uncommon. A lot of people have a fear of speaking in public.