• Delete Denzel Core plugin from Dashboard > Plugins
• If you activated the Envato Market plugin, so go to Envato market menu and update your theme.
• If you are not using Envato Market plugin, First you must download new theme package from Themeforest > Downloads tab then unzip it, then connect to your FTP and upload new Denzel theme folder to your themes folder instead old Denzel theme folder.
• After updating the theme, Install the new version of Denzel Core plugin from Appearance > Install Plugins
• Done

Its Important that after updating theme or plugins, Clear / Delete your browser Cache.