Grant drop permission on storedprocedure to user : How do I Grant drop permission of storeprocedure in sql server to user via script.

I tried the following  but it does not work

use XpressFeed_Dev
GRANT DROP ON procedure::getPartyDuns TO "INT\svc-w-corerefdata-de";

use XpressFeed_Dev
ALTER AUTHORIZATION ON [getPartyDuns]      TO  "INT\svc-w-corerefdata-de"; 