Remove the rules from the dashboard using you phone on lte. Or connect your laptop to the router or another network. But you already made it to the internet posting here...
In case the switch is offline, (Which should not happen because there is a explicit allow at the acl to the meraki ip addresses) you could factory reset it after you remove the rule from the dashboard
https://documentation.meraki.com/General_Administration/Support/Resetting_Cisco_Meraki_Devices_to_Fa...
