is there a way to DROP foreign key constraint ?

I'm unable to find the complementary function to 

ALTER TABLE t ADD FOREIGN KEY(id) REFERENCES pkt(pk);

I would try DROP TRIGGER, but I've also been unable to 
find a way to name the constraint ;(


the built-in help is both inadequate and inconsistent
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amphora2=# \h alter table
Command:     ALTER TABLE
Description: Modifies table properties
Syntax:
ALTER TABLE table [ * ]   ADD [ COLUMN ] column type
ALTER TABLE table [ * ]   ALTER [ COLUMN ] column { SET DEFAULT value | DROP DEFAULT }
ALTER TABLE table [ * ]   RENAME [ COLUMN ] column TO newcolumn
ALTER TABLE table   RENAME TO newtable
ALTER TABLE table   ADD table constraint definition

amphora2=# \h create table
Command:     CREATE TABLE
Description: Creates a new table
Syntax:
CREATE [ TEMPORARY | TEMP ] TABLE table (   column type   [ NULL | NOT NULL ] [ UNIQUE ] [ DEFAULT value ]
[column_constraint_clause| PRIMARY KEY } [ ... ] ]   [, ... ]   [, PRIMARY KEY ( column [, ...] ) ]   [, CHECK (
condition) ]   [, table_constraint_clause ]   ) [ INHERITS ( inherited_table [, ...] ) ]
 

amphora2=# \h column_constraint_clause
No help available for 'column_constraint_clause'.
Try \h with no arguments to see available help.
amphora2=# \h column constraint definition
No help available for 'column constraint definition'.
Try \h with no arguments to see available help.
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