Is government employee put a loss of pay with our intimate the concerned head

Namaste sir , I durgaprasad working as a grade 4 permanent govt employee in state government of andhrapradesh which is a non gazetted ... Sir iam b.tech graduate with good percentage and I cracked gate 2023 with 457 score ...I have a lot of chance in NIT college to pursue Mtech in my engineering stream .... For that I asked my head of the department to permit to study.. and he said as per the cca and subordinate rules I have not permitted to study because iam non gazetted post .. and also requested them to sanction loss of pay of my service for about 2year..for that they told me ,, u have no such option except the government allows to u to study with special G.O ,, that is a huge process and may not be my favour ...and now iam thinking to study my mtech and success in my career I would abscond from service without intimating them ...sir is it a good move?? Or else you please give suggestions how to study my mtech without losing my current govt job with loss of my pay ... Pls provide the suggestions.. is my contact number ..sir iam from poor family with big dreams to study and my job is very lower cadre even I have chances to go mtech my family problems strucking me I don't want to loose my hard earned job for m tech and also I don't want to loose my hard earned prestigious Gate rank for IIT and NIts for my low cadre job .I need both for safety purposes Kindly provide best suggestion which is even favourable infront of courts also I mean as per legally correct one .. Thank you sir and pls do needful