I have trained my dogs to "mind your manners" this is code for me anyway to stop licking your bits. I started training them by clapping which caught their attention and got them to stop and then gave the command. It has worked well for a bunch of dogs. But definately have her checked to make sure she doesnt have an uti or vaginal infection
She could have an infection and she is cleaning herself not knowing she is actually making it worse.
Take her to the vet and get her checked. Voice your concerns. If it is an infection he will give you a prescription she can take orally to help her heal. The infection is inside and only medication will clear it up. The vet can also give you a spray to apply directly to the area. Again, you have to take her to the vet to have her checked out for this, you can not self diagnose.
Dogs will do some licking as this is their way of cleaning themselves.
The best thing to do is get it checked out for the health and safety of your dog and for peace of mind for yourself. I hope everything is okay with her.
She is cleaning herself, you can't really stop her from doing that just make sure she is in her be or area that you can't see her when she does it or something. Its completely normal for dogs to do that.