They hunted down all of the libraries, collected all of the books inside, and burned them in massive bonfires, accidentally saving a total of like 3 books which had already been shipped back to Europe as trophies. I think there are also some remaining fragments of a few others. One Spaniard wrote about it:
> We found a large number of books in these characters and, as they contained nothing in which there were not to be seen superstition and lies of the devil, we burned them all, which they regretted to an amazing degree, and which caused them much affliction.
It's complicated in the sense that there were both people trying to burn and destroy anything and those trying to preserve the books and the language doing their own stuff in parallel.
It is worth noting that the friar who organized this book burning was recalled to Spain to stand trial on account of his actions.