Sometimes there are products in your shop that you don't want the slider widget to show. In order to specify these products, you can use the excluded product functionality.
Navigate to "Products" tab -> then click "Slider" on the left. Click the "Excluded" button to manage excluded products. The number in the parentheses shows how many excluded products are listed:
Start typing the product name in the search box. Click the desired product to add it to the list on the right.
There are two options:
The above options are controlled by the "Dynamic grouping" checkbox.
You can use one or two filters to select the products:
That's it, click save and wait for the changes to be published to your store (the blue progress line on top).