well I don't know much about ydl 6 ,I'm still trying to tackle gentoo
but ill try to do some research on it to try to help you.and I think to do delete that partition, go to the system click format harddrive, then click custom, then click allot 10gb for otherOs. It will reformat that partition, so if you wanted to try to install ydl again, thats only if you wanted.