Manual uninstall procedure for Cortex XDR agent. This will be required, when the agent connection is lost and is also removed from Cortex tenant without removing the agent from the endpoint.

Run Command Prompt as administrator
Change directory to agent directory
  C:\Windows\System32> cd “C:\Program Files\Palo Alto Networks\Traps”
Run the command "Cytool protect disable" from the command prompt. 
When prompted for password type the uninstall password (default Password1)
Post this, go to Settings->Add or Remove Programs, search for Cortex XDR, click Uninstall

This should uninstall the agent.