I was deleting the cache from apps and I ran acrossed many downloads of HTML's talking about certain words and phrases can I delete those to make more room or will it harm my phone?
HTML displays in your web browser, so it's probably cached data from sites you've visited. It won't do any harm to delete them, but if you go to the same sites, and they haven't been updated, those pages won't be downloaded again, they'll be read out of cache.