2 added code highlights
source | link
public void RemoveLanguageVersion(string rootItemPath, string languageName)
        {
            Language languageRemove = Sitecore.Globalization.Language.Parse(languageName);
            Item rootItem = Sitecore.Context.Database.GetItem(rootItemPath, languageRemove);

            if (rootItem != null)
            {
                using (new Sitecore.SecurityModel.SecurityDisabler())
                {
                    //Remove language version from root item               
                    rootItem.Versions.RemoveVersion();

                    //Remove language version recursively from child items of root item
                    foreach (Item child in rootItem.Axes.GetDescendants().Where(l => l.Language == languageRemove))
                    {
                        child.Versions.RemoveVersion();
                    }
                }
            }
        }
public void RemoveLanguageVersion(string rootItemPath, string languageName)
        {
            Language languageRemove = Sitecore.Globalization.Language.Parse(languageName);
            Item rootItem = Sitecore.Context.Database.GetItem(rootItemPath, languageRemove);

            if (rootItem != null)
            {
                using (new Sitecore.SecurityModel.SecurityDisabler())
                {
                    //Remove language version from root item               
                    rootItem.Versions.RemoveVersion();

                    //Remove language version recursively from child items of root item
                    foreach (Item child in rootItem.Axes.GetDescendants().Where(l => l.Language == languageRemove))
                    {
                        child.Versions.RemoveVersion();
                    }
                }
            }
        }
public void RemoveLanguageVersion(string rootItemPath, string languageName)
        {
            Language languageRemove = Sitecore.Globalization.Language.Parse(languageName);
            Item rootItem = Sitecore.Context.Database.GetItem(rootItemPath, languageRemove);

            if (rootItem != null)
            {
                using (new Sitecore.SecurityModel.SecurityDisabler())
                {
                    //Remove language version from root item               
                    rootItem.Versions.RemoveVersion();

                    //Remove language version recursively from child items of root item
                    foreach (Item child in rootItem.Axes.GetDescendants().Where(l => l.Language == languageRemove))
                    {
                        child.Versions.RemoveVersion();
                    }
                }
            }
        }
public void RemoveLanguageVersion(string rootItemPath, string languageName)
        {
            Language languageRemove = Sitecore.Globalization.Language.Parse(languageName);
            Item rootItem = Sitecore.Context.Database.GetItem(rootItemPath, languageRemove);

            if (rootItem != null)
            {
                using (new Sitecore.SecurityModel.SecurityDisabler())
                {
                    //Remove language version from root item               
                    rootItem.Versions.RemoveVersion();

                    //Remove language version recursively from child items of root item
                    foreach (Item child in rootItem.Axes.GetDescendants().Where(l => l.Language == languageRemove))
                    {
                        child.Versions.RemoveVersion();
                    }
                }
            }
        }
1
source | link

One option would be to execute a script on web database. Following link explains what code to be executed

public void RemoveLanguageVersion(string rootItemPath, string languageName)
        {
            Language languageRemove = Sitecore.Globalization.Language.Parse(languageName);
            Item rootItem = Sitecore.Context.Database.GetItem(rootItemPath, languageRemove);

            if (rootItem != null)
            {
                using (new Sitecore.SecurityModel.SecurityDisabler())
                {
                    //Remove language version from root item               
                    rootItem.Versions.RemoveVersion();

                    //Remove language version recursively from child items of root item
                    foreach (Item child in rootItem.Axes.GetDescendants().Where(l => l.Language == languageRemove))
                    {
                        child.Versions.RemoveVersion();
                    }
                }
            }
        }

http://www.bugdebugzone.com/2014/06/remove-specific-language-version-from.html