How to destroy actor by touching the screen anywhere?

You could consider the following:

  1. Create an Array of Actors in Level Blueprint. Make this array Editable from other Blueprints.
  2. You could ‘register’ every object you spawn with that array in Construction BP.
  3. You could then get the length of the array and selectively call Destroy Actor on n-1 or any other element.

This answers your question, but I would not recommend this approach.