According to campagnolo super record technology instruction,should I remove washers from pedals?if removed,will pedal destroy crank during riding?

Yes, do what Campagnolo says.

Some history on the subject. In days of yore it was steel pedal axles fitting to steel crank arms. There was no problem. About 90 years back aluminum cranks arrived. Pedals that had been good enough would cut, scar, possibly fracture the aluminum. This was mostly resolved by making pedals with flat and accurate faces to engage the crank arm. Campagnolo was the first to do this with complete reliability but it is really not that hard to accomplish. All modern pedals have flat and accurate faces. The only exceptions I have seen personally would be on very inexpensive bikes from India. Which still used steel cranks.

Those of us who use antique French bikes still use pedal washers. It is good engineering for the purpose. But even in that use case it is not really necessary.

Pedal washers have made a sort of comeback. I think it is bizarre. Some of it is connected to carbon fiber cranks. Fashion? Maybe someone with more recent shop experience will check in and discuss carbon cranks that have problems without washers. If that happens it should only be with El Cheapo cranks in early production runs. Campagnolo is telling you it does not apply to them.

Having two interfaces rather than one (crank to washer, washer to pedal) is imaginably problematic. In theory it could start to move. In olden days the crank was soft, the washer was soft, you wrenched hard, there was no problem. Now it is all more precise. Do what Campy says

Just out of curiosity, what do people with this setup (using manufacturer recommendations) do if they wanted to widen their pedal stroke width profile by say 4mms on each side? Just buy the +4mm pedals rather than add 4mms of washers?

In that case try to find 4mm spacers. A single spacer each side. A stack of thin washers is not a good idea. Few people want to do this, few even know how wide their pedals sit. But some want different spacing and do just as you say. It counts as a kludge.

The reason why Campagnolo doesn't want you to install a washer is because it would reduce the number of threads that are engaged, causing additional stress on the engaged threads, possibly leading to failure. This is also why Campagnolo calls out a minimum length for the pedal's threaded section.

The reason why you might want to use a washer: because the interface between the pedal and the crank is a fretting joint, which can produce cracks in the crank. Fretting damage to a washer is far less problematic than it is to a crank.

But you should only use a washer when the crank will accommodate it without reducing the engaged thread count.

Pedal extenders:

Nice, thank you for sharing. Just like to ask if the extender a universal for all types of bikes like the hybrids or trail bikes?

They work with any standard thread pedals (9/16" x 20tpi). I believe there are some that can adapt standard pedals to fit 1/2" x 20tpi crank arms, and perhaps the other way around as well.