WASHINGTON (Reuters) – U.S. Treasury Secretary Steven Mnuchin said on Friday that he would not meet a congressional demand for six years of President Donald Trump’s tax returns, all but guaranteeing a federal court battle with Congress over the records. “We are unable to provide the requested information,” Mnuchin said in a letter to House Ways and Means Committee Chairman Richard Neal, who subpoenaed Trump’s individual and business returns a week ago and set a 5 p.m. EDT (2100 GMT) Friday deadline for their delivery. …