These key caps are extremely easy to break. So going in prepared is key. :)
If you haven't taken a look at the internals of the key switch here's a picture that will probably help more than anything.
This image is a bit newer model, but the mechanism is largely the same. The key to damage free removal is to use something slim (like iFixit's Jimmy or an iSesamo) to get under the top edge of the key cap. That's the side with the clips, and the bottom edge has a little hinge in each corner that can take the posts on the key switch out too if you're not gentle.
There's also a Guide if you want a more step by step.
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