Yes, you can turn them off. Since I suspect the Netflix interface is different depending on the device you access it from (computer, iphone/ipad, Roku, smart tv, etc.), I wouldn’t give specific steps, but it should be pretty easy.
I thought I recently saw a message from Netflix that they were going to default to whatever subtitles or dubbing you usually use when watching their programs, unless you change it. Since I use subtitles a lot, I never noticed the difference.
I have occasionally seen some odd language subtitles or dubbing pop up in Netflix and Amazon Prime.