Yes, you can the same way Employers can rescind their offer letter to you. Do it professionally and immediately.Information about withdrawing from a course can be found here. There are many reasons why your employer may rescind a job offer. You may have failed a drug test. These sample forms may be useful when filing documents for the civil and family courts. If you have any questions, consult an attorney. Yes, an employer can sometimes rescind an offer even after the new hire has signed it. This isn't common but it does happen.