The procedure depends on your VPN and ad blocker provider, but if you use Surfshark, there are two ways to turn them off:
If you’re a browser extension user, you can press Disconnect to disable your VPN connection, then go to Settings → CleanWeb Settings and turn the desired toggles off to disable the ad blocking feature;
If you’re an app user, press Disconnect to disable your VPN connection, then go to Settings → VPN Settings, and turn the CleanWeb toggle off.