As describe by Ole, it is not possible for you to retrict a meber of confluence-administrators group to access the page. Mentioned by our documentation here, member of confluence-administrators group is a super user which will bypass any space permission.
However, if a page is restricted, the member of this group won't be able to access the page (hidden) without knowing the direct URL to the page as describe here.
Hope it clarify your doubts.
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