Hide list of available UIs

Hello Community
I need your assistance (agian), pleas.
I live on a small farm - my flat is on the top floor of the house we’re living in, my parents are living downstairs. Thus I created one sitemap for me (and my girlfriend) for our flat, and another one for all living in this hous, i.eg. for switching the outside floodlight,…
Ther is one issue now; If one enteres an incorrect URL, you’re automatically presented to a page listing all available sitemaps. Result thereof is, that everyone is presented to my “private” sitemp(s) as well, and not only to the “public” ones as intedned.
Is there any way to hide this page?

I’d like to use different sitemaps, with “complex” URLs instead of non-available authentication but the page shown above is not really a help in that case…

Thanks in advance!