Hi Arthur,
You need to deactivate your theme in the “Appearance > Themes” section by simply activating a different theme. Once you activate a different theme, you can delete your theme. Dont worry, your content will not be lost. (The translation files are located under languages folder in the theme folder.)
Then simply upload the new theme file in the “Appearance > Themes” section.
Once it uploads, choose to activate the theme.
Thanks
First of all thank you for your fast response. I am a bit concerned cause this theme was not setted up by me and I don’t know a lot about coding. So do I lost my settings (social media icons/ links, e.g.) when I delete this and update it as you advised?