How can I remove a tile from the benefits self-service landing page?

You need to set the tile's Visible property to No.

Here's how you duplicate the sample tile to create more tiles as per your requirement:

1. On the Home Page, click Configuration > Structure.

2. Create a Sandbox with Structure and Page Composer as tools.

3. Launch and enter into the sandbox.

4. Navigate to the Structure page from the Tools menu, and click Me.

5. Select the Quick Actions tab, Benefits.

6. Select the quick action for the tile that you want to remove.

7. Change the Visible property to No in the Edit Quick Actions page.

8. Click Save and Close.