public/library/Remove-PSTSSecureFile.ps1

function Remove-PSTSSecureFile
{
    param(
        [Parameter(Mandatory=$true)][string] $project,
        [Parameter(Mandatory=$true)][string] $id
    )

    process {

        _PSTSAPI `
            -project $project `
            -resource "distributedtask/SecureFiles" `
            -id $id `
            -method "DELETE"

    }
}