How to remove one tenant from lease?

[Yevgeniy Kovalenkov]

This is my first time renting a house. My tenant has called me a couple of days ago and told me that his wife had left him about a month and a half ago. He wanted to see if there is any way to remove her name from the lease so that she cannot come back. I really don't know any details about what had lead to her leaving.
As far as I understand, my hands are tied without her written consent.
Any input is appreciated.