Removing The D From A 1922 Penny

Let's preface it to say you need skills, otherwise it comes out as appeared damaged. Various ways are on the web, but I honestly cant condone ANY of them.

Way back in time when we were kids we used to doctor up all kinds of coins. For pennies we used an electric eraser and an eraser shield. We deleted part of the 4 in 1944D cents to make a 14D all the time since the 44's were so common. Removing the D in 1922 cents was just as easy. Removing dates, letters, part of the face, etc. was done for something to do mostly, not to fool people. Touching them up was done with gun bluing solutions to make the entire coin look OK. We use to doctor up all kinds of coins just for fun and put them back in change. And I suppose floating around in change for a few years also made them all look real. Being young coins were just for fun anyway.
Sort of like all the damage we used to do with them.

Actually the first cave people started with fire by rubbing stickes together. Then switched to electrical due to easier to start fires and right after that, due to all the cave walls full of writtings, they invented electric erasers to remove the ones not wanted.
In Engineering for a real, real long time drawings were made with pencil on either paper or cloth pressed with a wax substance that made them more perminent and translucent for printing copies.
Yes areas to be deleted were done with electric erasers and an erasing shield. The shields were made of metal with numerous varieties of holes for detailed locations for erasing. The metal absorbed the excess heat generated by the electric erasers.
They looked something like a scribber used to add names on tools or other person items.
Those days are now gone due to CAD. Computer Aided Drawings.

You are really looking at this as a Numistmatist, not a person of the ebay world, other such web sites, TV coin adds, etc.
For every person that knows about coins, there are possibly hundreds of millions that know nothing about coins. Remember there are over 300,000,000 people in the USA alone. Many, many of them are exposed to all kinds of stupid adds every day. I sometimes wonder how many even coin collectors have faked 22 Plains in their collections. How many have fake 09S VDB's, 1916D Mercury dimes, massive quantities of faked Morgan silver dollars and all in collections of coin collectors that THIHK they know coins.
As I said your looking at this from the view point of someone that might know coins, not the general populace.

Well, for those who are wondering what a strange question this was, please be relieved that I have no intention of doing this myself. I did not ask how to do it. I asked, within an historical context, how it would have been done.

It's simply something I've wondered about. And I'm surprised that this is not regarded as a common question. But know that no evil abounds here.

As far as the electric erasers go, how in the world would they be able to "erase" metal?

I am guessing it would be just like a coin would lose its detail by circulation. Just the friction of it being rubbed against anything will make the details of the coin fade away and if you concentrate that friction on one particular area and the friction was on that area long enough that area would soon lose its detail and be even with the surface below, if you did it longer than that area would be sunken in below the surface

This is sort of difficult to explain without actually showing someone. For one thing those electrical ereasers rotated a tubular type of erasing material at a rather fast rotation. The erasers came in all varieties of courseness. Some of the Engineering drawings that were supposed to permanent, never happens though, were done in INK. This means to remove the ink, you needed a courser material for an eraser.
Way back when in Engineering offices there was no such thing as Air Conditioning too. One nice trick was to add a propeller onto those tubular erasers and let them just run. In other words a made believe fan. Real fans were normally not allowed due to possible blowing expensive documents off a table. Also, back then windows opened and you would be amazed at how many times drawings flew out.
Electric erasers were used to do all sorts of things and removing stuff on coins was just one.

we used to put Lincoln Cents on the train tracks to get them elongated all the time when I was a kid. The train tracks was just across one street so we would walk over there all the time and have to walk the tracks looking for our coins we had placed on the tracks before the train came by