I'm a safety restraints engineer from Detroit. Spent 3 years of my life working for MOMO S.p.A. in Verona, Italy on Steering Wheels. I am not as familiar with your steeering wheel as I believe it's a Nardi. At any rate, I've seen them all so let's see if we can talk you through it. I would first check to see if the wheel has any small access holes from the side or backcover.

If there are holes but no evidence of a fastener (i.e. screw) inside, the holes are designed to relase the clips. By pushing a small rod through each hole and pulling up (one side at a time) you should be able to unsnap the unit.

I would tend to doubt this is the case due to the age of the unit.

If the wheel has holes with fasteners inside, they can be unbolted and the unit should snap out easier by hand. I would tend to doubt this also as your "DAB-Delete" wheel doesn't carry an airbag... so there's no real motivation to add them... besides they add cost. Nonetheless, I would check... they could have decorative plugs to camoflage them, so look carefully.

If the unit is held on by clips, watch out for a hidden third one at the bottom or 6:00 portion of the wheel Irregardless, this type of fastening does not need and was not designed to be slid around in order to be removed. It was assembled by snaping it into the wheel armature and consequently will come apart by carefully poping it out by hand (one side at a time). I would advise against using any tools to try to pop it loose unless you think you can be really really careful. If it comes down to just clips and there are no access points (as described above), the unit was designed to be removed by hand. My old Porsche wheel was done this way and it did unsnap with force when I took it off to re-wrap the wheel... but it was a doozy.

As far as being cautious, I don't blame you as the unit is old. Can you tell if the clips are metal or plastic? In addition do the clips run through the center of the horn springs (many DAB-Deletes are done this way)? Write me back when you get a chance. Regards, John