To update your theme you need to follow the below-mentioned steps.
1: Download Latest File
Goto your account at StyloThemes and download latest theme files.
2: Deactivate & Delete Current theme
Deactivate your current theme from Appearance > Theme (Simply activate any other default theme).
Now you can delete the current theme by clicking on it and hit the delete button in the popup.
3: Delete Stylo Core Plugin
Make sure to delete the StyloCore plugin. Go to Plugins > Deactivate StyloCore & Then Delete, you will see a delete link when hovering over the plugin name.
4: Upload Latest Theme & Activate
Now go to Appearance > Themes > Add New and upload the new theme file you just downloaded. Install & Activate and then Install StyloCore and any Recommended plugin by the theme.
5: Make sure to clear any cache before testing the updated theme.