Question

Press the ____ key(s) to erase one character to the left of the insertion point.

Answer 1

By pressing the 'DELETE' key with your cursor, you can erase a single character to the left of the insertion point. By pressing 'INSERT', then you would be able to replace characters to the left or right, whether you are deleting or adding a new character.
For more information, please follow the below links for reference:
http://www.schools.nsw.edu.au/learning/k-6assessments/csa6ictskills.php

Answer 2

To erase one character to the left of the insertion point it is the DELETE key.