Here's a detailed explanation for the removal of a stock steering wheel and installation of a rim blow steering wheel on a '72 Plymouth Scamp.

1.) Step 1: (Disconnect Your Battery before starting.)
Pry away the horn cap from the larger horn button. A smaller/slim flat head screw driver will work. Insert under edge and pry/slide carefully as to not force. It will give naturally, and work around the perimeter. *See Image No.1, and leave that brand emblem in the center alone. It's attached to the horn cap via a small plastic peg on the rear. Only thing you'll accomplish is breaking it. If you want to replace this or update; remove the horn cap and remove brand emblem from the rear.

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2.) Step 2: Remove the 3 screws from the horn button.

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3.) Step 3: Pull the Horn Button away from the housing. *The horn connection and ground wires will still be connected on the rear.

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4.) Step 4: Pull the Horn Connection away to disconnect, and unscrew the Ground Screw.

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5.) Step 5: Unscrew the Center Nut.

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*Next Steps involve a Steering Wheel Puller. A relatively easy tool to use, but they make some cheaper versions that I wouldn't recommend using on a 'classic'. They can make your work harder than it needs to be, and/or damage your original steering wheel.
I've posted a caution below on what to avoid. Heads up; most auto-parts suppliers will rent a proper tool set for use, so no need to purchase...

...what to avoid:

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6: Step 6: Use a proper bolt screw puller in the base of the wheel to remove the wheel. In this case, the 3/8" bolt. Apply leverage to the center bolt clockwise. Righty Tight/Lefty Loosey, but in this case the righty is what you want to loosen, applying leverage to the middle bolt to pull the wheel away from the column.

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7. Step 7: After you pull the wheel away, it's a good time to get familiar with that early technology inside. I recommend taking the time to add some friendly lubricant to the plastic catches of the Right/Left turn signals. Clean any old grease build up if necessary. Any harsh click/clack will soften. This early 'plastic' technology will still maintain a click/clack, but you'll be swerving through lanes like a champ.
That 'Horn Contact Wheel Connect' highlighted in the image below is a fun little wheel that rotates along the back plate, making constant ground contact when the steering wheel is in place.
(Clean any gunk off of this wheel contact point if there is any. Only takes a quick moment. You want good ground contact if you want a consistent horn.)
- - Most adaptable wheel replacement 'hubs' have a 'metal' wheel on the rear that should align here.

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8.) Step 8: Time for the adapter hub. In this case, a 'crush can' for the rim blow wheel. Center on the column. It should only fit and center at a single point due to the interior groove.
Re-Apply the center column nut and tighten to 45-60 lbs. of torque.
*I added a 3/8" black epoxy coated washer under the center column nut, but against the inside of the 'crush can' adapter, to account for more/less torque. Tighten it.
Remove the three tri-bolt nuts and prepare for wheel placement.

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9.) Step 9: Connect the wheel's horn connection to the connection inside of the hub . *Your wheel should be grounded from the rear contact of the hub.

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10.) Step 10: Place your new steering wheel onto the tri-bolts, and tighten.
*You're almost done. Get ready for that 'Horn Button.'

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11.) Step 11: Push that mock Horn Button into place, aligning the small pin on the rear with hole at bottom of wheel for centered placement. Enjoy your new cockpit.
*I entertained a few different wheel options with the intent to keep this pretty period correct. Both GRANT and GT have some 'tuff wheel' style options, but I just wasn't as pleased with those as I was with this rim blow option. It compliments the original dash perfectly in my opinion. The crush can hub does push the wheel out about 1" further than the stock, but nothing a slide back of the seat didn't resolve. If your pretty tall though, 6'+ this may be something to consider.

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