Deletion of the database finally did the trick. I also used a different database name, username, and password. Reinstall worked this time.
I do intend to upgrade to PHP 7 once we have finished building the new site. I just need to keep it on PHP 5.6 so that the current old site does not go down until we have finished copying content over and setting everything up. Once I do that, I will wipe out the old Drupal site, transfer WordPress to the root where Drupal is now, and then switch to PHP 7.
