Yes, you can cancel your flight without penalty both before and after the flight's departure.

Sadly, google's translation is far from good. What it should read is:
1.- The regulations for the most restrictive segment apply for the whole trip
2.- IN CASE your ticket is not refundable, you are entitled to request a refund of airport fees/taxes (note: for the unused segments). On some countries you may be charged a service fee when purchasing the ticket, which is not refundable (note: not on the Chile site)

The table below does read: "permitted without penalty" for both changes and refunds.

Take note, however, that even though there is no penalty for changes, you may incur on a fare difference depending on the fare you paid and what is actually available when you request the change.

happy travels!