I bought a set of spark plugs for my 2002 Lesabre and was going to put them but found out I could not get the wires of of the old plugs. Car has about 40k miles. Is there a secret to getting them off?

The boots have likely fused to the plug insulators. You can try to twist the insulators to break them loose, then pull them off. Using a coating of silicone dielectric grease inside the boots of the replacement wires will not only help keep the boots water sealed, but can help in removal later.