How do you cut tile straight which is laid down?

Am removing an old floor *(tile) in kithchen which runs into adjacent room. Thing is, thetile is not straight, and wish to keep tile in adjacent room, but remaining tile in kitchen has a 90 deg angle corner jutting in kithcen. So, how do I make a nice neat straight cut on the "border" tiles to make all even/straight? Some "fine" type of wet saw? Dremmel?