No, you can't. A "by" condition can't be met if only some of the required actions are performed. The conditions for this [On Play] [When Digivolving] [When Attacking] effect require you to place the specified number of cards as the bottom digivolution cards.

This effect prevents cards stacked on top from being trashed by <De-Digivolve> or other effects, and cards stacked on the bottom can't be trashed by effects such as those that trash digivolution cards.