In the context of sustainable development and the growing importance of recycling, fibre reinforced thermoplastics have gained significant attention in various industries. Efficient welding of these materials is crucial to ensure their structural integrity and to extend their life cycle, which is essential to reduce their environmental impact. This study investigated the resistance welding of a glass fibre reinforced thermoplastic composite with polyamide 6.6 matrix (PA6.6). The focus was on developing a de-welding-on-demand concept for applications such as large solid structures. The main problem with current disassembly strategies is that the composite parts are often damaged during the debonding process. Therefore, the primary objective of the research was to weld the PA6.6 composite with a modified heating element for controlled de-welding without damaging the composite parts. Two welding configurations were used for this purpose: PA6.6 welded with a PA6 heating element and as a reference: PA6.6 welded with a PA6.6 heating element. The PA6 heating element, which has a lower melting temperature, was tested for its effectiveness as a de-welding-on-demand concept as well as its lap shear strength at room temperature. The study involved testing the welds at room temperature and at an elevated temperature of 220°C where the parts are to be disassembled. A key finding was that using the lower melting PA6 in the heating element significantly improved the lap shear strength of the welds compared to the PA6.6/PA6.6 configuration at room temperature. Additionally, at 220 °C, the lap shear strength of the hybrid PA6.6/PA6 configuration dropped to only 6% of its room temperature lap shear strength, demonstrating the functionality of the concept. The main benefit is that by applying heat locally, only the PA6 is melting, while PA6.6 adherends stay consolidated due to their higher melting temperature. Micro-CT and SEM analysis provided a more detailed insight into substrate damage during debonding. The results indicate that when using a PA6 heating element for welding PA6.6 composite parts, strong and reliable joints can be formed which can be selectively disassembled at high temperatures when required, by reheating of the heating element, either by electrical resistance heating or by induction heating. This approach is in line with the goals of sustainable composite manufacturing for better maintenance, repair or reuse purposes. Future work should aim to further refine process parameters to improve reproducibility and performance within the resistance welding process of de-welding concepts. A large structure will be fabricated to demonstrate the applicability of the concept.