Delete Portal Row
Deletes the selected portal row (which deletes data in a related record).
Delete Portal Row [No dialog]
Perform without dialog prevents a message box from displaying when the script step executes that asks the user to confirm the deletion of the portal row.
This script step is also supported in web publishing and in a FileMaker Server scheduled script.
Originated in 
FileMaker Pro 6.0 or earlier
Use the Go to Portal Row script step to control which row is selected. (If no portal row is selected, nothing happens when this script step executes.)
Important  You cannot undo a Delete Portal Row script step.
The following script selects the first portal row in the current record and then deletes that row with no confirmation dialog box.
Go to Portal Row [First]
Delete Portal Row [No dialog]
Related topics 
Script steps reference (alphabetical list)
Script steps reference (category list)