It's hard to give you an exact herbal remedy for frequent urination without knowing what the root cause of the frequent urination is. It could be an irritable bladder. It could be a urinary tract infect or a kidney infection. It could be a lack of healthy beverages. It could be that you body needs a detox or that your diet/environment are toxic. It could be that you're pregnant.
It could be any number of things, all of which need to be known before someone can give you a good herb for clearing up frequent urination. If you can give more clarity to your situation, I am sure we can find the right remedy for you.