The Siri icon appears in both the menu bar and the dock. If you are not interested in Siri, you can easily hide it.
To hide the Siri icon in menu bar, head to “System Preferences” > “Siri” and uncheck the box next to “Show Siri in menu bar.”
If you want the Siri icon out of the Dock, just click and hold on the icon, then drag it out of the Dock to remove it. Siri will still work with a keyboard shortcut, but will be out of your way.