[Iska]

На PowerShell:

Код:

Get-ChildItem -Path 'C:\Temp' -Include '*@*.*' -Recurse | ForEach-Object -Process {
    if(-not $_.PSIsContainer) {
        Rename-Item -Path $_.FullName -NewName "$($_.BaseName -replace '@', '-')$($_.Extension)" -Force
    }
}