Dear Jin, since instant book is the default when you start out as a host it can cause lots of problems, I'd recommend turning it off so you have more control as you are learning how to host. You will have an issue with airbnb if you decline the booking but a super cheap listing can attract problem guests besides leaving you without a profit. I'd try to decline the booking request if possible- with an apology and explanation that you are a brand new host still learning the system & then fix the price. Only cancel the booking if there's no other way out & accept that airbnb won't be pleased but there are worse things in the world- like your listing being left a mess! Best of luck , Sally