As long as there was no intellectual property infringements, perhaps you could sell the house plans that coincide with the windows, or something along those lines without crossing any ethical or legal lines.

Thankyou for the response. Yes, we do have our house plan and are ready to sell it if needed. But where do I start ? Whom to approach?

Is this a custom home? Any building going on around it? Ask the builder and window distributor if they have any suggestions. If that doesn’t work I’d try FB Marketplace and eBay.

Craigslist or donate them to a Habitat for Humanity ReStore

Knowing your location might help.

Thankyou all for your response. I will look into Craigslist , eBay

I'm sorry your plans fell through but I'm going to be honest with no sugar coating, you're going to take a loss on those windows and if they are custom sizes and color you'll get even less. I've sold dozens of new doors and windows on Craigslist and still have more to sell, but based on my experience Craigslist shoppers aren't looking to buy a house full of windows and build to utilize the windows. They are looking for a bargains and just a few for an addition, remodel or cabin. Are your windows custom or more standard size windows? And color matters, white exterior sell the fastest while other colors are slow to move. What's the color?

I have a $1200 Pella 3'x6' arched window in sandstone I can't get $100 for and a $4000 beautiful entry door with sidelights I can't get $1000 for because it has a 7 1/4" jamb. I hate to be the voice of reality here but Craigslist will be a hard sell if you sell them as a package. If you bundle you will lose much more than selling them by the piece and need to do what the people are doing in the link seaborman gave to ebay.

You could use facebook's market place to peddle those windows also but if you use craigslist don't respond back to any text wanting you to type in a code to verify you're not a scammer. It's the way they hijack your phone number to use for other scams. I picked up all I've sold from people like you who's plans fell through, most for little or nothing and they just wanted the stuff out of their garage and life so you're not alone.

Kevin Thankyou for your honest feedback. We are still processing the fact that our plans fell through and now we have these windows . Most are custom sizes with black exterior. I will keep in mind your suggestions while I list them to sell .

"Most are custom sizes with black exterior."

Unfortunately you will end up with pennies and the dollar. No one will want to design their home around someone else's custom sized windows unless the deal is absolutely smoking. Plus they will more than likely not get the Pella warranty for the windows.

Where are you located?

Sasha, can you share the sizes of the windows or the link to where you’re selling them? thanks.

Do we presume that you've discussed this with Pella? Given the slow delivery for many building supplies, I thought they might be able to help you.