There is no hard disk, as in spinning magnetic storage.<p>The step-by-step teardown at <a href="https://www.ifixit.com/Teardown/iPhone+X+Teardown/98975" rel="nofollow">https://www.ifixit.com/Teardown/iPhone+X+Teardown/98975</a> shows that the Toshiba TSB3234X68354TWNA1 64 GB flash memory is on the outside of the logic board sandwich; step 12.
iFixit is the place for tear-downs; here's their video on the iPhone X: <a href="https://www.youtube.com/watch?v=3oz-Q3tn70k" rel="nofollow">https://www.youtube.com/watch?v=3oz-Q3tn70k</a><p>Though I think you'll be disappointed, that stuff is probably soldered on and can't be removed.