Send a copy of the U.S. Constitution, with the First and Tenth Amendments highlighted, to those who signed the petitions "Strip the Citizenship from Everyone who Signed a Petition to Secede and Exile Them" and "Deport Everyone That Signed A Petition To Withdraw Their State From The United States Of America."
The First Amendment guarantees the right to freedom of speech, and to petition the government.
Secession is not forbidden by the constitution, so falls under the tenth amendment.
The Tenth Amendment states that matters that aren't explicitly forbidden in the Constitution, are to be designated to the States and the People.
Secession is an fundamental American Principle.