[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint.Client")
[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint.Client.Runtime")


Function Get-ClientContext([string]$Url,[string]$UserName,[string]$Password)
{
    $SecurePassword = $Password | ConvertTo-SecureString -AsPlainText -Force
    $context = New-Object Microsoft.SharePoint.Client.ClientContext($Url)
    $context.Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($UserName, $SecurePassword)
    return $context
}


Function Uninstall-AppInstance([Microsoft.SharePoint.Client.ClientContext]$Context,[Guid]$AppInstanceId)
{
    $appInst = $Context.Web.GetAppInstanceById($AppInstanceId)
    $appInst.Uninstall()
    $context.ExecuteQuery()
 }



$UserName = "jdoe@contoso.onmicrosoft.com"
$Password = Read-Host -Prompt "Enter the password"
$Url = "https://contoso.sharepoint.com/"
$AppInstanceid = New-Object Guid("XXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")  #specify App Instance Id here

$context = Get-ClientContext -Url $Url -UserName $UserName -Password $Password
Uninstall-AppInstance -Context $context -AppInstanceId $AppInstanceid
$context.Dispose()