DROP PROCEDURE — remove a procedure
DROP PROCEDURE [ IF EXISTS ]name[ ( [ [argmode] [argname]argtype[, ...] ] ) ] [, ...] [ CASCADE | RESTRICT ]
   DROP PROCEDURE removes the definition of an existing
   procedure. To execute this command the user must be the
   owner of the procedure. The argument types to the
   procedure must be specified, since several different procedures
   can exist with the same name and different argument lists.
  
IF EXISTSDo not throw an error if the procedure does not exist. A notice is issued in this case.
nameThe name (optionally schema-qualified) of an existing procedure. If no argument list is specified, the name must be unique in its schema.
argmode
      The mode of an argument: IN or VARIADIC.
      If omitted, the default is IN.
     
argname
      The name of an argument.
      Note that DROP PROCEDURE does not actually pay
      any attention to argument names, since only the argument data
      types are needed to determine the procedure's identity.
     
argtypeThe data type(s) of the procedure's arguments (optionally schema-qualified), if any.
CASCADEAutomatically drop objects that depend on the procedure, and in turn all objects that depend on those objects (see Section 5.13).
RESTRICTRefuse to drop the procedure if any objects depend on it. This is the default.
DROP PROCEDURE do_db_maintenance();
This command conforms to the SQL standard, with these PostgreSQL extensions:
The standard only allows one procedure to be dropped per command.
The IF EXISTS option
The ability to specify argument modes and names