Absconding from company after joining in 2 days

I have recently joined in an organization which is an Inc 2 days back. But today I got offer from good MNc company which has started interview process before receiving any offer . I want join in this MNc now how can I proceed in leaving current inc which joined 2 days back. In offer letter there is a clause mentioned that if I resign in 30days of joining I have to serve 4 months notice or I have to pay to buy notice period. I confused what to do now. Any suggestions would be appreciated