How do I delete ALL sites in iWeb?

I got a new MBA and set it up using a backup from my old MacBook. I wanted to remove the sites from iWeb on my old MacBook (leaving them only on the MBA). I was able to delete them all except one. “Delete” is grayed out. I thought maybe it had something to do with being the last one, so I hit “undo” to bring back the last deleted site. Then I tried to first delete the site that was previously last. This time I got the message: “This site will be removed from iWeb. Would you also like the site removed online? Your site will be permanently removed.” My choices are “cancel” or “remove.” If I hit cancel, the site still remains in iWeb. I don’t want to hit “remove” for fear it will remove the site from online. I realize I could probably re-upload it from my new MBA, but it’s a very large site with a lot of media. Is there a way to remove the site from the old iWeb without also removing it from the Internet as well? And why was I able to remove the other 4 sites from iWeb without having this issue?
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Cameron