I would just remove it and replace it with a simple round sink. It's not that difficult to do. https://www.diynetwork.com/videos/replacing-a-bathroom-sink-0136465
Is it a sink that is inserted into a countertop or is it molded as part of countertop? If it's inserted, you can remove if and replace it with any sink that you like. If it's part of the countertop, the whole top will need to be replaced. If you want to cover the sink and countertop to used for another reason, you can simply put plywood over the top then finish it with tile or paint to use as a vanity with no sink. I'm not sure which you meant so I thought I'd toss out other ideas. Wishing you the best.
That does sound very cool. Unfortunately, I wasn't able to find it. If it wasn't long ago, you may be able to check your history on your computer. Just use Ctrl h to see your history and scroll down until you find it. Good luck!
I found an article that might help. It's a DIY Vanity Makeover using a Concrete Overlay