If you have excluded them from the analysis due to not completing the survey, I would exclude them from the demographic information. All you have to report is for example, 50 individuals participated in the study, but 5 was excluded from the analysis due to not completing the survey.
I would rather exclude them from the sample since they did not participate fully. However, if the number of those that stopped at the demographic questions is significant (let say above 10). You may need to investigate why they discontinued, perhaps there are questions in your survey that did not go well with them ethically.