Premature graying of hair could be due to stress, smoking, nutritional deficiency
, pernicious anaemia, thyroid
disorders and hereditary factors.
If the cause is genetic, nothing can be done.
Improving diet, avoiding stress and smoking and ruling out treatable underlying causes like thyroid disorder or anaemia may halt or slow down the progression of premature canities.
To treat the existing gray hair, best option is to color them or leave them as such. However as you specifically want them to be removed, here are few options
1) electrolysis for hair removal
( routinely done, easily available at all dermatology centres)
Below mentioned are only available at advance cosmetology centres.
hair removal( selectif pro)
3) diode lasers or IPL with application of liposome bound melanin
Hope that answers your query. Take care.