Technically, yes, but it is not a very courteous thing to do and you may be on the hook for costs such as credit-check and appraisal fees from each lender, depending on their policies. Originating and underwriting a loan takes a lot of time and care from several dedicated professionals. Locking rates with a lender implies that you are going through with the loan, which is how they get paid. If you cancel at the last minute, they have wasted their time and that company or lender may not be willing to work with you in the future.