Because of low internal storage I am unable to download windows 10 update. what should I do?

I am having LUMIA 640XL. I updates it to windows 10 once. But after some days new update came and I am unable to install that update because it require 776 MB free in internal storage and even after deleting apps in internal storage I don't have enough space because my system memory is near about 6.38 GB. Please provide me help to download my new windows 10 update asap.

WIndows 10 update - 10.0.10586.545

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