According to the TEDx speaker guide, which you can download here:
Slides can be helpful for the audience, but they are by no means necessary or relevant to every talk. Ask yourself: Would my slides help and clarify information for the audience, or would they distract and confuse them?
If your slides help clarify the information for your audience, include them. If not, and if you’re using the slides as a crutch, then forget about the slides.