Modify Part List Content

What version of NX are you using?

Also, by "erase the components that I don't need", I assume you mean delete the line in the parts list, not delete the component itself - is this correct?

Have you tried the Plist.RemoveObject method? I worked up a small example that seems to work (not thoroughly tested). The code will remove the selected component from the first parts list found.

Option Strict Off
Imports System
Imports NXOpen
Imports NXOpen.UF

Module Module1

Sub Main()

Dim theSession As Session = Session.GetSession()
Dim theUfSession As UFSession = UFSession.GetUFSession()
If IsNothing(theSession.Parts.Work) Then
'active part required
Return
End If

Dim workPart As Part = theSession.Parts.Work
Dim lw As ListingWindow = theSession.ListingWindow
lw.Open()

Const undoMarkName As String = "Remove component from parts list"
Dim markId1 As Session.UndoMarkId
markId1 = theSession.SetUndoMark(Session.MarkVisibility.Visible, undoMarkName)

Dim myPlistTags() As Tag
Dim numPlists As Integer
theUfSession.Plist.AskTags(myPlistTags, numPlists)

'lw.WriteLine(numPlists.ToString & " Parts list(s) found")

Dim myComponent As Assemblies.Component
If SelectComponent("Select Component", myComponent) = Selection.Response.Cancel Then
Return
End If

theUfSession.Plist.RemoveObject(myPlistTags(0), True, myComponent.Tag)
theUfSession.Plist.Update(myPlistTags(0))

lw.Close()

End Sub

Function SelectComponent(ByVal prompt As String, ByRef selObj As TaggedObject) As Selection.Response

Dim theUI As UI = UI.GetUI
Dim title As String = "Select a Component"
Dim includeFeatures As Boolean = False
Dim keepHighlighted As Boolean = False
Dim selAction As Selection.SelectionAction = Selection.SelectionAction.ClearAndEnableSpecific
Dim cursor As Point3d
Dim scope As Selection.SelectionScope = Selection.SelectionScope.AnyInAssembly
Dim selectionMask_array(0) As Selection.MaskTriple

With selectionMask_array(0)
.Type = UFConstants.UF_component_type
.Subtype = UFConstants.UF_all_subtype
End With

Dim resp As Selection.Response = theUI.SelectionManager.SelectTaggedObject(prompt, _
title, scope, selAction, _
includeFeatures, keepHighlighted, selectionMask_array, _
selobj, cursor)
If resp = Selection.Response.ObjectSelected OrElse resp = Selection.Response.ObjectSelectedByName Then
Return Selection.Response.Ok
Else
Return Selection.Response.Cancel
End If

End Function

End Module