This sounds fairly straightforward. Can we assume that the 'lines' you refer to are in fact paragraph's? There are no 'lines' in a Word document, other than as an artefact of text flow.
Code:
Sub Macro1()
Const strWord As String = "word to find"
Dim oRng As Range
Dim oFind As Range
Set oFind = ActiveDocument.Range
With oFind.Find
Do While .Execute(FindText:=strWord, MatchCase:=True, MatchWholeWord:=True)
oFind.End = oFind.Paragraphs(1).Range.End
Set oRng = oFind.Next.Paragraphs(1).Range
oRng = Replace(oRng, "(", "")
oRng = Replace(oRng, ")", "")
oFind.Collapse 0
Loop
End With
lbl_Exit:
Set oFind = Nothing
Set oRng = Nothing
Exit Sub
End Sub