Hi shauryahanda,
GMAC's policies regarding test cancellations due to Covid-19 can be found here:
https://www.gmac.com/why-gmac/gmac-news ... oronavirusAccording to GMAC, if your appointment was cancelled because the Test Center was closed, then you should receive a full refund. However, from your message, it does not sound as though that describes what you are asking about. If you want to cancel an appointment that you have made - but has NOT been cancelled yet - then that might ultimately be a Customer Service issue, so you should contact MBA.com directly to ask for assistance.
GMAT assassins aren't born, they're made,
Rich