Windows (PowerShell)
Get-ChildItem -Recurse -Filter "*.py" | Where-Object { $_.FullName -match '\\migrations\\' -and $_.Name -ne '__init__.py' } | Remove-Item
Get-ChildItem -Recurse -Filter "*.pyc" | Where-Object { $_.FullName -match '\\migrations\\' } | Remove-Item


Mac | Linux
find . -path "*/migrations/*.py" -not -name "__init__.py" -delete
find . -path "*/migrations/*.pyc"  -delete