WP sites mix up,

[the-active-one]

I have a big problem I have two sites for many years unused, australianactivealliance.org and themangotreerevisited.blog I also have two websites on SiteGround using WP they are Australian-active-alliance.com.au also The mangotree revisited.com.au how do I delete the first two sites, they clash on Google are not used I have been paying for the Domain names on WP, I believed the payments were for the Siteground sites as they use WP, what happens if I close the first two sites.