Who says the government needs to remove them? There could be a grace period of a year or maybe several years, during which people already owning a gun can apply for a license and receive the necessary training. Those who don't want to get the license can come in to prove they made the firearm unusable. Anyone else owing a gun can be made liable after that grace period. This would minimize necessary resources.

Also, a proper government should be able to focus on several things. And I do think daily school shootings is something worth focusing on.