It's great to hear that you recognize your current skill level and are thinking about the best course of action. In this situation, it would be best to have an open and honest conversation with your team lead about your concerns. Express your gratitude for the support and guidance you have received, and discuss any potential training or development opportunities that could help you improve your skills. Resigning may not be the only solution, as there may be ways for you to grow and contribute effectively within your current role. Ultimately, the decision is yours to make, but it's important to consider all options before taking any drastic steps.