public boolean unmap(String path, String httpMethod) {
        return routes.remove(path, httpMethod);
    }
Unmaps a particular route from the collection of those that have been previously routed.
Search for previously established routes using the given path and HTTP method, unmaps any
matches that are found.

@param path       the route path
@param httpMethod the http method
@return <tt>true</tt> if this is a matching route that has been previously routed
@throws IllegalArgumentException if <tt>path</tt> is null or blank or if <tt>httpMethod</tt> is null, blank,
                                 or an invalid HTTP method
src/main/java/spark/Service.java