How to cancel timeshare contract?

You have to look at the contract you signed to see how it can be canceled. Your state might have additional rules but if you signed the contract while out of state the other state's laws might apply. In California, you would have only a few days at best [3 business days]. Normally it is very difficult to void timeshare contracts as that is how the resort makes its income [plus annual membership fees]. You would have to show fraud, misrepresentation, etc, if the resort was not willing to cancel, but even then it would probably charge you a fee to do so. there a large number of companies who advertise they can get you out of the time share interest, but you have to either pay them several thousand dollars or they will just list the property and wait for someone to buy it on the after sale market [where the cost is often less than 50% of what the resort charges]. Many of these companies do absolutely nothing to market your time share interest.

Depends upon how you own. Contact the owner services department of your timeshare and inquire about either feeding the timeshare back or reselling.