If you don't need it, you can deactivate plugin Newsletter in Admin -> Plugins.
To change texts, image, background image for this section or remove it, you can change it in Admin -> Appearance -> Widgets
To translate other texts of this section, go to Admin -> Translations -> Theme translations.
You can modify it in Admin -> Appearance -> Widgets.
You can click on "Delete" button to remove widget from footer sidebar or change the name, selected menu.
If you want to add more widgets, just drag and drop from the left side to sidebar.
If you want to disable widgets in the product detail page, you can set product layout in Admin -> Appearance -> Theme options (tab Ecommerce) and change Product Single Layout to full width.
If you want to disable widgets in the blog page, you can set blog layout in Admin -> Appearance -> Theme options (tab Blog) and change Blog Single Layout to full width.
And go to Admin -> Pages (select page Blog) then set Template to full width.