I have 5 Yoast sitemaps that I have added to webmaster tools. I then added smart crawl which is great. But what should I do about sitemaps. I turned off Yoast sitemaps on their dashboard. Is this wise? Should I delete their sitemaps and add domin/sitemap.xml instead.
Can the two work together?
There shouldn't be two SEO plugins active at once as this might cause issues. They both serve the same purpose so they can be conflicting (or the data they produce while active together it might be "corrupted" in some ways).
So, after switching to SmartCrawl deactivating Yoast would be the essential thing to do. As for sitemaps, that depends on Sitemap(s) URL(s). If the URL didn't change (because sitemap from "old" plugin get overwritten by the sitemap from "new" plugin) - there'd be no need to make any changes as Google would just "re-crawl" it overtime.
However, in this case, I think it would be best to first submit the new sitemap to Google to make it crawl it and then actually remove the older sitemaps. The sitemap data is pretty much the same but the sitemaps themselves might be a bit different so in order "not to confuse" crawlers this would be a good way to go, I think.