You can always decrease the spam score of your domain if you add more informative content to it, decrease the number of external links on this website and increase the number of backlinks from different niche related domains. If you check about Spam Score, you will notice that it includes a lot of different factors, including content on the website. You can check backlinks for this domain, create a list of backlinks pointing to this domain, if most of them are spammy, it would be better to search for other domain, as it will be hard to get them deleted, also it could be the reason the domain authority increased for this domain and if you delete those backlinks the domain authority will decrease as well.