Deleting ical downloads

Hello all,

I have some downloads from the internet that I would like to delete but I'm unsure if I delete them will they also disappear from my calendar. So for example I use a site called volunteer Spot and when I book myself in there is an option to add the dates to your ical. I have done this for quite a while now and its a great tool and saves time but if I delete the download will it also delete on my ical?