Ask the vendor. It depends where you purchased it, and how long you own it. In the USA, EU, AU, and in some other lands you usually have between 14 to 30 days to change your mind, and return the goods without justification.
Before returning the watch, you should do the master reset to factory settings with deleting all data. Not only it is polite to the vendor, and to the potential future owner, but it also protects your privacy.
