It is a simple matter to call your United States Congresspeople and ask them to compel the President to resign.

Calling 202-224-3121 will give you the Capitol switchboard, and providing your zip code will direct you to your representatives in the House of Representatives and in the Senate.

You can also find Free Speech for People’s petition to impeach the president here.  As of this writing, it has just shy of 1.4 million signatures.