If the Heritage Foundation's goal was to merely demonstrate the possibility of voter fraud, then they should have saved themselves the effort. Of course it's possible, and of course it happens; and when it happens, it tends to get discovered and handled. They have a much higher bar to clear to convince me that the issue warrants any greater scrutiny than it already receives.
As for the removal of millions from various voter rolls, you'll have to be more specific; most of these are administrative tasks being performed as they are meant to be performed, and very few of the millions removed are non-citizens. Most are removed because they've died, or moved, or failed to respond to inquiries, etc. Oregon, for example, recently moved to remove 800,000 voters from their rolls, but again, this was an administrative move; the voters were already marked as inactive and inactive voters in Oregon do not receive ballots. Removing them wasn't a priority, but now it is, so they're doing it. The point is that millions being removed is not really a cause for alarm or a sign of fraud; it's just a sign that you're unaware of how the system works.
As for the removal of millions from various voter rolls, you'll have to be more specific; most of these are administrative tasks being performed as they are meant to be performed, and very few of the millions removed are non-citizens. Most are removed because they've died, or moved, or failed to respond to inquiries, etc. Oregon, for example, recently moved to remove 800,000 voters from their rolls, but again, this was an administrative move; the voters were already marked as inactive and inactive voters in Oregon do not receive ballots. Removing them wasn't a priority, but now it is, so they're doing it. The point is that millions being removed is not really a cause for alarm or a sign of fraud; it's just a sign that you're unaware of how the system works.