Use a washrag when you shower and clean your body once, rinse, and do it one more time. Use it also with soap on your hair and face. You may shampoo after.
After the shower, you can use the same washcloth and pour rubbing alcohol and rub it all over your body, paying particular attention to your armpits.
Then use a good deoderant containing Triclosan, which kills bacteria. This will help better than any deoderants that do not contain it.
Also, make sure all your whites, tshirts and undies are washed with bleach. I noticed that I smell quicker if I wear a tshirt that was not washed with bleach. I personally always wear a white tshirt underneath my shirt. I, of course, change both daily.
Do this and I hope your armpit oder goes away like mine did. Thank you.