How to disable subtitles on PC

Subtitles are provided by Official OpenSubtitles  Add-on. To turn them off (forever ;-) ) you have to uninstall OpenSubtitles Add-on. You will find instruction how to uninstall Add-ons here

https://stremio.zendesk.com/hc/en-us/articles/360021348391-How-to-install-uninstall-Add-ons

Another solution is to go to the Settings and change default subtitles language to some exotic language like one in the screenshot