Drop foreign keys

Hi,

I created some  references with foreign keys. But now I have to drop
some of the references. What is the way to do this? Is there a command
for this? Or have I drop the table  and recreate it?
Postgres gave the references names like "RI_ConstraintTrigger_494516".
If there is a way to drop them one by one how do I get the information
on which foreign key point these Postgres names?

All references are created like this:
... constraint tPerson_FK03 foreign key (titel)
   references tTitel (tnr)
   ON UPDATE CASCADE ON DELETE RESTRICT ...

Greetings,
Andreas