How to remove the hard drive from the my book enclosure

How can I remove the 500 GB hard drive from the my book home edition enclosure, since the esata connection has just failed ? I use it to install and boot to several Linux on parttions other than the storage ones, and so I use it mostly by esata and only some connected by the USB which does work fine. So then I plan to install that hard drive into a new drive enclosure unit, thanks.

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