Clear previous state's parameters from Soft Back Button history?

Okay so I have a state that accepts a parameter. When it is available, it hits the server, pulls data and pushes that data into the next state so a user can take action on that data.

I have something like:

"/usersearch/:userId?" 

as example:
"/usersearch/12345"

Which works fine and I can pull the user information on landing on this page. What I do though is if that userId is not there I land on a search page to allow a user to search by text input. If the userId is present then I pull the information by Id and send the user to a new state:

"/employee/usermod"

The back button wants to take me to:

"/usersearch/12345"

I need the back button to just be:

"/usersearch/"

How can I overwrite the last back history item to have NO state parameters?

Thanks!