You cannot delete an Asset, however you can archive an Asset which works in the same way.

To archive an Asset in the Web Portal > Assets > Asset Register > Select the checkbox for the Asset you want to archive > Select Archive at the bottom of the page.

If you would like to view more Assets in the list so that you can delete more at a time, then you can select the amount that you would like to view in the list by clicking on the Rows per page option in the bottom right of the list. The maximum number you can view in a list is 100.