Is it Okay to delete old folders from under my 'VirusDefs' section of my Norton Security File

I am in desperate need of more room on my C drive and I notice that a whopping 3GB is being taken up with 7 files (modified between August and October this year.

Each file name resembles a date and seems to contain the same types of files,(DAT, IDX, FLT etc.)  so I was wondering if it was okay to delete some of the older ones or do I need all 7 files?

Any help would be much appreciated as my lack of space is beginning to look critical.

Many thanks.