I keep them and ignore.
You might need them later, for example the view stuff is needed for sending HTML and Markdown based emails or notifications.
Later you might need to publish some api docs, so the web routes might come in hand for that.
Just use the api middleware stack and token guard and you will be fine most of the time.
The only thing you might want to tweak is exception handling, if the client making the request doesn't send the headers that Laravel needs to know they expect a JSON response it might send a redirect or render a HTML error page. Take a look into you exception handler (./app/Exceptions/Handler.php) and some of the auth related middleware to be sure you always return a JSON no matter if the request have all the headers Laravel needs to know the request expects a JSON response.