how can i remove dried ceramic tile adhesive off top of tiles?
If the tiles are glazed, you should be able to use a paint scrapper or razor blade to gently remove the adhesive. Some adhesive remover such as Goo-Gone might help as well. Just don't scrape too hard, and be careful if using a razor blade!
If the tiles are not glazed, this process is not going to work.
mineral spirits or paint thinner gets off some kinds of mastic.