If your application is approved, you will receive an Employment Authorization Document (EAD) from the USCIS. The EAD will be mailed to the address listed on the Form I-765.
Authorization May Not Be Rescinded
Once authorization to engage in OPT has been granted and an EAD has been issued, you may be able to cancel that authorization only under certain conditions.
Generally, authorization may not be rescinded or canceled and you will lose the employment benefit even if you have valid reasons for not having been employed, such as unexpected delays in completing degree requirements, inability to find an appropriate job, or loss of a job. Once permission to work has been granted, it is gone regardless of subsequent occurrences.