Remove Dead Sites

How do I remove sites from my Site Management list? I have a number of site that are no longer up anymore and I’d like to clean up the list.

https://wordpress.com/plugins/jetpack

Self hosted wordpress install at willfoster.doesntexist.org/blog needs to stay. I used to run two other sites at http://www.williamgfoster.com/blog and http://www.williamgfoster.com/wedding, had jetpack installed on them. No longer own the domain and no longer wish to manage these sites. Can you help me clean this list up?

https://wordpress.org/plugins/jetpack/