Invoke-CancelAdoBuildsAndJobs.ps1

function Invoke-CancelAdoBuildsAndJobs
{
	param(
		[Parameter()]
		[ValidateNotNullOrEmpty()]
		$AzureDevOpsPAT,
		$OrganizationName,
		$ProjectName
	)

	$ErrorActionPreference = 'Stop'

	$AzureDevOpsAuthenicationHeader = @{Authorization = 'Basic ' + [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(":$($AzureDevOpsPAT)")) }

	$Uri= "https://dev.azure.com/$($OrganizationName)/$($ProjectName)/_apis/build/builds?statusFilter=notStarted&api-version=5.1"

	$PendingJobs = Invoke-RestMethod -Uri $Uri -Headers $AzureDevOpsAuthenicationHeader -Method get -ContentType "application/json" 
	$JobsToCancel = $PendingJobs.value

	if($JobsToCancel)
	{
		foreach($build in $JobsToCancel)
		{
		   $build.status = "Cancelling"
		   $body = $build | ConvertTo-Json -Depth 10
		   $urlToCancel = "https://dev.azure.com/$($OrganizationName)/$($ProjectName)/_apis/build/builds/$($build.id)?api-version=5.1"
		   Invoke-RestMethod -Uri $urlToCancel -Method Patch -ContentType application/json -Body $body -Header $AzureDevOpsAuthenicationHeader
		}
	}
	else
	{
		"Nothing queued, nothing to cancel."
	}
}
Invoke-CancelAdoBuildsAndJobs -AzureDevOpsPAT '' -OrganizationName '' -ProjectName ''