Delete Windows Live Mail Contacts - Already tried everything

I'm an old user of Windows Live Mail, I've been using it for as long as I remember. My question is regarding the contacts that have been created through all this years. I still have contacts of the time I was 7! I want to erase them. I tried to follow the advices of "selecting and erasing" and the eliminate button grays out.

Now, something REALLY IMPORTANT TO MENTION: My account is not linked to facebook, nor twitter, nor anything. But the contacts from my account cannot be erased.

I'm attaching an screenshot

 HELP PLEASE!