概要

using UnityEditor;

public static class Example
{
    [MenuItem( "Tools/アセットバンドル名全削除" )]
    private static void Hoge()
    {
        AssetDatabase.StartAssetEditing();

        foreach ( var assetPath in AssetDatabase.GetAllAssetPaths() )
        {
            var assetImporter = AssetImporter.GetAtPath( assetPath );

            if ( string.IsNullOrWhiteSpace( assetImporter.assetBundleName ) ) continue;

            assetImporter.SetAssetBundleNameAndVariant( null, null );
            assetImporter.SaveAndReimport();
        }

        AssetDatabase.StopAssetEditing();
        
        foreach ( var n in AssetDatabase.GetAllAssetBundleNames() )
        {
            AssetDatabase.RemoveAssetBundleName( n, true );
        }

        AssetDatabase.SaveAssets();
    }
}