Have you joined the offer with paycut? If not, just say you got a better offer and are withdrawing your acceptance. If you have already joined, there's generally a probation period of about 3 months where you can quit with a notice period of a week. This is two way of course as they can ask you to leave with just a week of notice. Anyway, you can probably just say you got an offer with work from home or something they are not willing to compromise over. You can also ask them if they can match your salary before you do that though. They just might.