Do you know how does yeast infection occur? If no is the answer, then let me tell you a fact of human body. Two types of bacteria lies in our body- good bacteria (that helps our body to perform basic functioning) and bad bacteria (that harms our body and causes infection).
Yeast infection happens when the number of bad-bacteria in a certain area becomes more than the number of good bacteria.
So, there are two ways out of this situation- either anyhow increase the number of good bacteria, so that they may themselves take care of the bad ones or directly reduce the number of bad bacteria.
If you want to increase the number of good bacteria in your body. Then consult your doctor and get few drugs prescribed for yourself (as per your body) for increasing the number of good bacteria.
There are also few natural ways to do that. If you want to follow that natural approach then you may find few herbs as per your need. Get them approved by your practitioner, then you can use those herbs.
However, if you yearn to go away from yeast infection by destroying the bad bacteria, try using some antibacterial gels, or apply some medically approved anti-bacterial soap on the infected area.