Can you say no for a tooth extraction ?

Tooth extraction is not always necessary. A dentist will most likely give you the option of removing the nerves from that tooth and filling in the tooth / fixing it up. However, this method does not always work - Not only does this way have multiple appointments to do, but there is a likelihood that it can cause an infection or not take away the problem.

Of course you can. They're not going to hold you down and do it forcibly.

It's also a service you have to pay for.

That being said, if they're recommending an extraction, there is likely a reason. That reason (such as an infection) could become much more severe if not dealt with so talk to your dentist about treatment options.