public function downgrade() {
		$template = $this->getTemplate($this->getTemplateName());
		$fieldgroup = $template->fieldgroup;

		$fg = $this->wire('fieldgroups')->get($template->name);
		$minNumberToError = $fg->id == $fieldgroup->id ? 2 : 1;

		if($fg->numTemplates() >= $minNumberToError) 
			throw new WireException("Cannot delete $template->name, because it's fieldgroup is used by at least one other template.");

		// Remove all pages of that template
		$selector = "template=$template, include=all, check_access=0";
		$this->eachPageUncache($selector, function($p) { $this->pages->delete($p, true); });

		// Delete fieldgroup and template
		$this->templates->delete($template);
		$this->fieldgroups->delete($fieldgroup);
	}