How can I safely remove blackberry plants before they start to grow this spring?

I moved in this house in November. There are a lot of wild blackberries growing in the woods behind my house. The problem is they are growing right up against, over and through my chain-link fence. Those thorns are horrible! They have ripped me and my dog's up. Is there some protective gear I can put on to permanently remove them? Is there a very specific blackberry plant killer? s/