I ripped the carpet off our stairs a few weeks ago. It wasn't hard, but it was time consuming to get all of the tack strips and staples up. (Do a search, and I'm sure you'll find some of the same tutorials I used. Pulling up a runner shouldn't be any different than dealing with fully carpeted stairs.) The big thing I'd be worried about in your case would be scratching or gouging the wood. Some of the tack strips were pretty hard to pry up. I was working on unfinished pine, so it's possible your experience would be different. But I did have some scratches and gouges that I had to fix when I refinished them.

If you do decide to tackle it yourself, the best tip I read was to get a diagonal cutting pliers to get the staples up. After struggling through removing them the first day, I searched for a better way and found that idea. It made the rest of the stairs go so much faster. (You use them to pull, not cut, but once in a while the staples accidentally got cut and I just pulled the 2 halves out separately.)

I do this every other day so it's become a lot easier for me over the years lol, but what I do is I start with the first step on top. I use pliers and a box cuter. I recommend using gloves if it's your first time as well.

Now with the box cuter, cut the carpet from end to end. When you've done that use the pliers to get a better grip and tug hard and fast. It should come right off. For me the longer the carpet is, the easier it becomes to pull. After removing the carpet you'll still have some staples sticking out from underneath each stair lip, you can remove those with the pliers.

To removed the pad, You can just rip it up by hand. It comes right off but you'll leave the staples behind tho, with a scraper you can scrape them right out easy. Use a crowbar to remove the tack strips. Shove the crowbar under each nail and bam it'll come right up. Don't worry about scratching the wood because if you're going to keep them as wood and not replace the carpet you'll have to completely sand and stain them all over again. They use staples for the carpet and pad, and nails for the tack strips. You'll have to get them sand and stained again. If the carpet company that installed the carpet on your stairs told you that it wouldn't damage anything underneath and that you can have the carpet removed and go about your day with out having to do extra work to the stairs they lied.

Omega has the right idea. The main point here is that if you are planning to tear out the runner and be able to live on beautiful hardwood stairs, it is not the case. Some work will need to be done as nail holes, scratches, tack strip, etc has affected the wood. Sanding and staining is going to be the best option after tear out. OR choose a new carpet that you like and will clean better for the stairs and replace the runner.