there are 2 ways

right click on the database and choose properties and then in one of the screens there will be a recovery mode box (i don't have sql 2000 installed so i can't screen shot it)

or the easier way is using an SQL SCRIPT

ALTER DATABASE xxx SET RECOVERY SIMPLE

in older versions of sql you could also use the sp_dboption command

be sure to read up in books on-line before you make the change - just so you understand the implications.