The Delete command deletes one or more records from the database. The set of records involved are taken by the WHERE clause.
NOTE: Don't use SQL DELETE to remove Vertices or Edges but use the DELETE VERTEX and DELETE EDGE commands that assure the integrity of the graph.
DELETE FROM <Class>|cluster:<cluster>|index:<index> [LOCK <default|record>] [RETURN <returning>] [WHERE <Condition>*] [LIMIT <MaxRecords>] [TIMEOUT <timeout>]
Delete all the records with surname equals to 'unknown' ignoring the case:
delete from Profile where surname.toLowerCase() = 'unknown'
To know more about other SQL commands look at SQL commands.