Sure it can but it's not ever as easy as simply hitting the delete key. It typically requires a product like the now infamous Bleach Bit to overwrite the drives many many times, which is time consuming, and leaves a blank slate behind.
Did they Bleach Bit (etc) every system, and re-install, which would typically require touch labor? I doubt it.
But even if they did, my point was, with the amount of money Trump has in his stop the steal war chest, he should be able to hire forensic investigators equivalent to those who WROTE Bleach Bit to analyze these systems for mistakes, or proof of use. Specialists in this field of expertise, not just computer guys with decades of experience. Thanks.
There are several utilities (most free) to wipe storage devices. They perform over-writing different bytes in multiple passes.