In order to delete multiple products, you'll first have to create a segment that includes all those products. 

Note: you need admin rights to be able to delete several products at once.

1. A first step would be to define fitting rules. For more information on segments, click here. In case you'd like to delete all your products for example, your segment would be as follows:

2. Once you've created a segment that includes all products you'd like to delete, simply select that segment in the dropdown menu next to the search field. You'll then see an 'Actions' button at the top right of your overview screen, below 'Add product'. 

3. If you click on this button, you'll have the option to delete all products in this segment.