Removing "Edit Chart" link in iframe

I’m having trouble removing the “Edit Chart” button on a chart posted on my blog. Can anyone provide insight why “link=false” is not working?

Here’s an example with the link

and without

Thanks @etienne. I did notice that this only worked for sharing='public' and not sharing='secret'. Is this on purpose as a feature of 'secret' or an oversight?

It should working with the sharekey: