A method for disassembling two ultrasonically welded elements, one of the elements comprising, at a surface opposite the other element, an energy director that concentrates the heating during ultrasonic welding and forms a material junction between the two assembled elements after the ultrasonic welding. The method includes the steps of positioning a wire between the two assembled elements, so as to be secant to the energy director, said wire having suitable mechanical characteristics allowing it to cut the junction formed by the energy director and moving the wire between the two assembled elements so as to cut said junction.