Please find This Tutorial: https://d5creation.com/themeupdate
WordPress Contents are stored in a MySQL Database, not in any Theme Files. So, Changing Themes, Updating Themes, Removing Themes don’t remove any Data.
For removing the Read More link from the Slider, Please download the Latest Version again even you already downloaded, Update your site and Leave the Image Link field blank from WP-Admin > Appearance > GREEN EYE Options > Slider