I want to remove the 40 year old burglar bars from my front door & por

They are most probably attached with screws? Just take the screws, or whatever is attaching them, out and patch the holes with wood putty. Sand the places smooth then you can paint.

I agree with removing the screws but if they are rusted, be careful not to damage or strip the screw during removal. If the screw is 'frozen' in place by rust and won't budge, try dissolving the rust and loosening the screw by pouring Coca-Cola over it (as this beverage is known for loosening rust from metal objects). Once removal is complete, fill the holes where the screws once attached the bars. Good Luck!

Ditto. You can then install a more secure lock if needed. Some doors have more than one lock and / or more than one kind, requiring keys or extra burglar tools not often carried by thieves.

If you don't have a key, you will need a hacksaw as well as a good screwdriver, lubricant, maybe bolt cutt CocaCola is good. So is WD40, to lubricate the screws or bolts so you can get them out easier. Let the lubricant sit for half an hour before you try the screws. Before (if) you call a locksmith, ask at your closest police and fire department if they would come by your house with the equipment they would use to get the bars off. Be ready to show ID and proof you own the house. Best wishes 😇