What is the process to remove isolation and restore network connectivity to affected system in case of false positive? Can I do it myself?

Field Effect can remove the isolation through an interface. For security reasons, there is currently no plan to expose this functionality in the Portal.

When a system is isolated, we modify the Windows firewall to block all inbound/outbound traffic except for the endpoints connection to Field Effect. This allows us to revert the isolation once the issue has been remediated. Isolations are implemented via Windows Firewall rules and could be manually removed by an administrator logged into the computer.