DROP SYMMETRIC KEY (Transact-SQL)
Removes a symmetric key from the current database.
If the key is open in the current session the statement will fail.
If the asymmetric key is mapped to an Extensible Key Management (EKM) key on an EKM device and the REMOVE PROVIDER KEY option is not specified, the key will be dropped from the database but not the device, and a warning will be issued.
The following example removes a symmetric key named GailSammamishKey6 from the current database.
CLOSE SYMMETRIC KEY GailSammamishKey6; DROP SYMMETRIC KEY GailSammamishKey6; GO