Can you simulate a VPN disconnect in order to test the 'seamless tunnel' killswitch?

Hello I connect to my vpn provider via openvpn. My system is Win 10. A week ago I experienced a vpn disconnect and my pc switched to the regular internet connection (Im certain about this!) I had ‘seamless tunnel’ enabled in openvpn which I think should act as a killswitch. I’d like to run a test where I simulate a VPN disconnect and the make sure the ‘Seamless tunnel’ kills my PC’s internet connection entirely. IS this possible? Thanks

Find the VPN endpoint you are connecting to, and block the IP at the firewall.

Only allow you vpn in outgoing connections in your routers firewall. And you are always save