DROP SIGNATURE (Transact-SQL)
Drops a digital signature from a stored procedure, function, trigger, or assembly.
DROP [ COUNTER ] SIGNATURE FROM module_name BY <crypto_list> [ ,...n ] <crypto_list> ::= CERTIFICATE cert_name | ASYMMETRIC KEY Asym_key_name
Is the name of a stored procedure, function, assembly, or trigger.
Is the name of a certificate with which the stored procedure, function, assembly, or trigger is signed.
ASYMMETRIC KEY Asym_key_name
Is the name of an asymmetric key with which the stored procedure, function, assembly, or trigger is signed.
Information about signatures is visible in the sys.crypt_properties catalog view.
Requires ALTER permission on the object and CONTROL permission on the certificate or asymmetric key. If an associated private key is protected by a password, the user also must have the password.
The following example removes the signature of certificate
HumanResourcesDP from the stored procedure
USE AdventureWorks2012; DROP SIGNATURE FROM HumanResources.uspUpdateEmployeeLogin BY CERTIFICATE HumanResourcesDP; GO