Remove background hdr on AR

Questions
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1

I load model.glb and hdr file to show on website. But when use AR to view on mobile, I want space real instead background hdr.
How to remove background hdr when view on AR?

renderer = new THREE.WebGLRenderer({ antialias: true, alpha: true });
renderer.setPixelRatio(window.devicePixelRatio);
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.toneMapping = THREE.ACESFilmicToneMapping;
renderer.toneMappingExposure = 1;
renderer.xr.enabled = true;
renderer.outputEncoding = THREE.sRGBEncoding;
container.appendChild(renderer.domElement);

		// Get the XRSession object
		const xrSession = renderer.xr.getSession();

		// Enable the torch on mobile devices
		if (xrSession) {
			xrSession.updateRenderState({ environmentIntegration: "none" });
		}

		document.body.appendChild(ARButton.createButton(renderer));
2

Can’t you just set scene.background to null when entering the XR session?