Powershell - Start or Stop SQL service on remote server

 You can use below script to start and stop remote SQL services.

* Just for one computer

(Get-Service -ComputerName YOURCOMPUTERNAME -Name 'SQLAgent').Stop()
(Get-Service -ComputerName YOURCOMPUTERNAME -Name 'SQLAgent').Start() 

* For multiple computer

$ServerList = Get-Content "DRIVE\ServerNames.txt"

ForEach ($ServerName in $ServerList)
{
    Write-Host $ServerName
    (Get-Service -ComputerName YOURCOMPUTERNAME -Name 'SQLAgent').Stop()
    (Get-Service -ComputerName YOURCOMPUTERNAME -Name 'SQLAgent').Start()

}