A completed student attempt can be permanently deleted from EAS > Attempts.
Find the required attempt and click Delete.

EAS asks for confirmation before deleting the attempt.
Deleting an attempt permanently removes the student’s attempt and its associated responses. For Audio Response questions, the associated audio recordings are also deleted.
Deleting an attempt cannot be undone. An attempt should therefore only be deleted when the student record and its responses are no longer required.
If the result is needed for assessment records, keep the attempt rather than deleting it.
Before deleting an attempt, check the student name, quiz title, score, and completion information to make sure that the correct attempt has been selected.