You cannot disable the high-res image page that appears at
/image/29430360799. Anyone who really wants to view your highres images can go to
/archive, click a post, and change /post/XXXXX in the URL to /image/XXXXX. The only way to securely prevent people view highres images is to, well, not upload highres images. You should be able to replace your current highres images with lowres ones by editing your current posts.
If you just don't want to link to these highres image pages (which would still exist), remove {LinkOpenTag} and {LinkCloseTag} in your theme. You can simply remove them or you can replace them with <a href="link of your choice"> and </a>, respectively.
Also, because /image/XXXXX is the fallback URL for {LinkOpenTag}, if you set a click-through link in your photo posts, {LinkOpenTag} will point to the link you set instead of /image/XXXXX.