How to destroy and securely dispose a Hard Drive even FBI/NSA cannot recover your data? 

This was a thing over a decade ago, maybe longer. Back when drives were MFM, RLL etc. Back then, it was possible to recreate data by reading from the edges of the tracks which were not always erased/overwritten. However, since IDE and SATA, so far as I know, no one has recovered data that has been overwritten by the normal OS. The tricky bit is the difference between 'Deleted' and 'Overwritten'. When you delete a file on Mac or PC, often times the actual file is not deleted. What is deleted is the name of the file in the directory, and the location. The is akin to deleting a chapter of a book by whiting out the chapter name and number from the Table of Contents. If you flip through the book, the chapter is still there and readable. To securely erase, you want to overwrite all the tracks that the file is on, with either random data, all zeros, all ones, etc. Old DoD had a protocol for overwriting the entire disk with a minimum of 7 seperate passes of all zero's, all ones, and random data, in some order. As mentioned this was because older drive technology was based on wider data tracks on the disks, and and erase or delete file command would change 95% of the track location, but that small area not erase could still technically be recovered. With the newer drives, much smaller tracks, and much finer read/write heads, there is no way read the 'margins' of the tracks to snoop on old data. So, get a good Open Source program like DBAN, etc, which will do a low-level format of a drive, and run a couple of cycles of filling all the tracks with random data. Actually, someone has a large bounty IIRC for years now, where they will payout if anyone can recover data from a standard Mac/PC low-level format alone. CIA/NSA can't keep that secret.

I suggest using sandpaper on the platter, putting holes in it with a drill, then cutting it in half and bending the pieces.

Pop the discs off put the motor hub in a lathe chuck and scrape the shiny datafoil off saving the chips with a vacuum cleaner. Recycle the aluminum platters hub and case as cast aluminum, then dissolve the datafoil first with NaOH to remove sluminum then water rinse then in HNO3 to remove cobalt samerium and nickel, finally in aqua regia to remove platinum. The silver grey powder left over is rhodium.❤

How many HDDs can you cut with one entire saw blade?

Circuit boards have bad chemicals so wear lung protection if using the chopsaw

What’s the powder you are putting in the bag at the end?

The brand of the saw is DeWalt. Not sure why the dude went and censored it lol but ok

Sorry for the long post above. TL;DR, do a "Low-level Format" from your OS on the drive. Every Data-Recovery company in existence will tell you they are not going to be able to recover anything. And its doubtful the CIA, NSA, FSB, etc are going to either. If you know about the technology, it makes sense. If you think it is magic, then you will destroy working hardware for no good reason.

I just drop mine into 2000' of seawater.

I'm just watching for curiosity

Back at the turn of the century one of Britain's major psychiatric clinics upgraded their computers and dumped the old computers in the yard. I was given permission to take anything I wanted. All the installed hard drives had had their circuit boards cut ... but there were a couple of unused drives. I used the circuit boards from these on the drives in the computers ... and was able to access EVERYTHING the clinic had stored on their system ... patients records, communications between psychiatrists from all over the world, research data, etc. The clinic specialised in child psychiatry ... from what I read I came to the opinion that they were moulding children's behaviour to fit in with their theories ... a sort of "psychiatric witchcraft" seemed to be going on. Recently this clinic has been sued by people who were encouraged by the clinic, before they reached puberty, to undergo gender reassignment .

Can you not just simply snip off the strip connecting the circuit board to drive? will that suffice?

I would bet that stretch it and put it in a strong acid for hours would make a difference.

Do it the American way, use an AR-15 and a Tub of Tannerite! Bless Canada!

what about just burning the damn thing!!!

Umm sounds like you have something to hide...smh