Trending @Cognizant; How to get early release from project

I have offer in hand from xyz organisation. Before interview I told them my notice period is only 30 days, but it’s actually 90 days. Will they give me early release? I’m working as a Non billabe in project and only 2 weeks ago i allocated to this project. There is no such that much dependency of mine. Can someone tell me how to deal with this situation? And what if they don’t give?