Cleaning Up the Mess – Automating the Removal of Unused Project Parameters in Revit

class ProjectParameterData
{
    public Definition Definition = null;
    public ElementBinding Binding = null;
    public string Name = null;
    public bool IsSharedStatusKnown = false;
    public bool IsShared = false;
    public string GUID = null;
}

// Get all project parameters
static List<ProjectParameterData> GetProjectParameterData(Document doc)
{
    if (doc == null)
        throw new ArgumentNullException("doc");

    if (doc.IsFamilyDocument)
        throw new Exception("doc can not be a family document.");

    List<ProjectParameterData> result = new List<ProjectParameterData>();

    BindingMap map = doc.ParameterBindings;
    DefinitionBindingMapIterator it = map.ForwardIterator();
    it.Reset();

    while (it.MoveNext())
    {
        ProjectParameterData newProjectParameterData = new ProjectParameterData
        {
            Definition = it.Key,
            Name = it.Key.Name,
            Binding = it.Current as ElementBinding
        };

        result.Add(newProjectParameterData);
    }

    return result;
}
Code language: PHP (php)

public void CheckAndRemoveUnusedParameters()
{
    UIDocument uidoc = this.ActiveUIDocument;
    Document doc = uidoc.Document;

    var families = new FilteredElementCollector(doc).WhereElementIsNotElementType();
    List<ProjectParameterData> projectParametersData = GetProjectParameterData(doc);

    List<string> unusedParams = new List<string>();
    IList<ElementId> paramsToBeDeleted = new List<ElementId>();

    foreach (var param in projectParametersData)
    {
        bool isUsed = false;

        foreach (var elem in families)
        {
            try
            {
                Parameter p = elem.LookupParameter(param.Name);
                if (p != null && !string.IsNullOrEmpty(p.AsString()))
                {
                    isUsed = true;
                    break;
                }
            }
            catch (Exception) { }
        }

        if (!isUsed)
        {
            unusedParams.Add(param.Name);
        }
    }

    DeleteUnusedParameters(doc, unusedParams);
}
Code language: PHP (php)

private void DeleteUnusedParameters(Document doc, List<string> paramNames)
{
    IEnumerable<ParameterElement> allParams = new FilteredElementCollector(doc)
        .WhereElementIsNotElementType()
        .OfClass(typeof(ParameterElement))
        .Cast<ParameterElement>();

    IList<ElementId> paramsToDelete = new List<ElementId>();

    foreach (var param in allParams)
    {
        if (paramNames.Contains(param.GetDefinition().Name))
        {
            paramsToDelete.Add(param.Id);
        }
    }

    using (Transaction t = new Transaction(doc, "Remove Unused Parameters"))
    {
        t.Start();
        foreach (var paramId in paramsToDelete)
        {
            doc.Delete(paramId);
        }
        t.Commit();
    }
}
Code language: PHP (php)