A procedure is owned by the user who created it; that user can execute it without privilege.
Permission to execute the procedure can be granted to other users using the GRANT EXECUTE command. For example, the owner of the procedure new_dept allows another_user to execute the procedure using:
GRANT EXECUTE ON new_dept TO another_user
To revoke permission to execute the procedure, execute:
REVOKE EXECUTE ON new_dept FROM another_user