Need consultation on name changing

Respected sir,

my friend has changed his name for spiritual initiation , to choose ascetic path , which he did thru Gazette notification of the respective state . but now he rolled back to normal society life . he wish to change the name once again to apply for pan card and other relevent materials . can he able to do ? if so whats the procedure ? what documents we need to submit ? how long it will take ? (now he residing in tamilnadu)