Laser hair removal systems are looking for pigment. Unfortunately gray hair has ZERO pigment so there is nothing for the laser to pick up. If you have an area where the hairs are mixed we can still laser the area and pick up the dark hairs but the grays will remain.
The only options for gray hair is to get electrolysis or spray the hairs with a Meladine spray. The spray needs to be sprayed on to the hairs that are kept short during the process twice a day for 3 weeks (2 weeks if the hairs are blonde and not gray). The spray can be bought online. I have been in this business for 9 years now and have seen mixed results with the spray. I think that many people that do not get good results with the spray do not use it consistently enough. I have had many who it has worked for. If interested in finding out more let me know.