PostgreSQLDatabase.DeleteLargeObject
From Xojo Documentation
Method
Deletes the large object identified by oid.
Notes
PostgreSQL requires that all large object operations be performed inside of a transaction. Therefore, you must start a transaction before you perform your first large object operation:
db.ExecuteSQL("BEGIN TRANSACTION")
After you have performed your last large object operation, you should close the transaction, like this:
db.ExecuteSQL("END TRANSACTION")
Please see the PostgreSQLLargeObject class for information on how to work with large objects.
Example
Delete a large object: