There are multiple ways to get rid of a side stitch while you're running.
One technique that people use is trying to pay attention to what foot they're landing on while they're running. Most people tend to land on their right foot when they exhale. But what happens with that is with your liver being on the right side of your body, it puts pressure on your liver, so it will actually pull on your diaphragm and that can cause side stitch. One thing you can try to do is when you're landing on your left side, try to exhale forcefully and see if that helps over a little bit of time.
Another thing you can try to do is pull over to the side and try to stretch on that side of the stitch where it's happening and really take a deep breath and breathe into that side of the stitch. Try to keep walking and keep moving and eventually, it should go away.
Another thing that people try to do is have a banana at the beginning of the day. Some people believe that trying to have that little bit of extra potassium will help to prevent the stitch because it's believed that an electrolyte imbalance can cause that side stitch. Or, if you'd like, try to have a sports beverage with a little bit of sodium in it. So usually throughout your run, as you're sweating and you're losing that sodium, that can cause a little bit of cramping or a little bit of side stitching.
But ultimately, you need to find out what works for you and you're only going to find out unless you try.