Problem with upgrading

I tried the automatic update a long time ago and was never able to get it to work. I had to get the hosting company to restore it. Now I’m trying to do it on my own and I’m at the point of deleting wp-includes and wp-admin. wp-admin deleted ok but when I try to delete wp-includes I get:

Failed to delete contents of folder “ftp://caddotx:[email protected]:21/public_html/wp-includes/js”

Now what?