Cannot Cancel My Vacation

I booked a vacation from November 2-6 when I was going to Indonesia because I did not know about the Internet access. Now when I am here and there are no issues, I was trying to cancel the remaining of my vacation, but I cannot.
When I selecting the day or dates I want to cancel in the future, I cannot, WHY?

@luck said
I booked a vacation from November 2-6 when I was going to Indonesia because I did not know about the Internet access. Now when I am here and there are no issues, I was trying to cancel the remaining of my vacation, but I cannot.
When I selecting the day or dates I want to cancel in the future, I cannot, WHY?

Go to my vacation settings and click the current vacation on the calendar and I think the option to cancel then comes up. Once selected your vacation will cease at 0000hrs GMT and any unused days will be available for later use.

Alternatively see your travel agent.
(There may be a small cancellation fee.)