How to remove ListView's add item animation?

These animations are called transitions and they are part of ListViewStyle. To change it right click on ListView control in the designer and select Edit Template > Edit a Copy.... This will add the built-in style to your XAML.

The following part of the style is of interest to you:

<Setter Property="ItemContainerTransitions">
    <Setter.Value>
        <TransitionCollection>
            <AddDeleteThemeTransition/>
            <ContentThemeTransition/>
            <ReorderThemeTransition/>
            <EntranceThemeTransition IsStaggeringEnabled="False"/>
        </TransitionCollection>
    </Setter.Value>
</Setter>

I'm not sure which animation exactly you dislike but try removing AddDeleteThemeTransition and/or EntranceThemeTransition from TransitionCollection. It should do the trick.

Don't forget to make sure the modified style is applied to the desired ListView.

It might be in the default ItemsPanel.

You could try something like this:

<ListView.ItemsPanel>
    <ItemsPanelTemplate>
        <VirtualizingStackPanel>
            <VirtualizingStackPanel.ChildrenTransitions>
                <TransitionCollection/>
            </VirtualizingStackPanel.ChildrenTransitions>
        </VirtualizingStackPanel>
    </ItemsPanelTemplate>
</ListView.ItemsPanel>

Why though do you want to go against the fluid part of the Fast and Fluid thing of the design language? Are you trying to implement something more bland than the templates or are you planning on adding your own transitions?

Thanks to Damir's answer, this is how I did it. Just add this in your App.xaml

<Application...>
    <Application.Resources>
        <ResourceDictionary>
            ...
            <Style TargetType="ListView">
                <Setter Property="ItemContainerTransitions">
                    <Setter.Value>
                        <TransitionCollection/>
                    </Setter.Value>
                </Setter>
            </Style>
        </ResourceDictionary>
    </Application.Resources>
</Application>