Remove credentials

We have a few servers that are secured using Basic Auth. They are published on a webtop. When the user clicks the first one they are prompted for credentials. Once they are successfully authenticated, the browser stores those credentials and they are not prompted again for any of the other portal based apps. This causes issues because user logs on with one account, accesses a resource with another and then accesses another resource with yet another. Is there a way to have APM strip the credentials from the browser and have each published app prompt for credentials regardless of what has already been done?