www to non-www with .htaccess

I currently have this .htaccess: pastebin.com/gfg5ujL0
On the bottom there are the lines to redirect http urls to https.
But if I go to my site using https :// www..... it will not redirect to non-www site.
It may cause a problem for Google I think.

Do you guys kindly know which is the line to add to make this redirect?
I searched a lot and each modify I apply makes my site offline!

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