If you have a missing link you can not print or PDF the documentveith good picture quality. You need to relink first then embedd. But embedding links will make your document huge is is mostly bad practise...
I found this post via a google search, and found the answer elsewhere, so I thought I'd share the solution here to help other searchers.
Like Frans said above, you need to link your images in InDesign rather than embedding images. However, if you're trying to unlink text frames, that can be done safely.
Open the links panel, select the text frame link, and right click it. You'll see "unlink" as an option. When you click "unlink," the text item will disappear from the links panel, because it's no longer linked.
If you don't select a text link, you won't see the "unlink" option.
Hope this helps, Google searchers.