You have to read xml from string (database field), then to use Linq to find proper node/element and finally to rmove it:
Sub Main
Dim xcontent As String = "<?xml version='1.0' encoding='utf-16'?>"
xcontent = xcontent & "<ArrayOfString xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xsd='http://www.w3.org/2001/XMLSchema'>"
xcontent = xcontent & "<string>a</string>"
xcontent = xcontent & "<string>b</string>"
xcontent = xcontent & "<string>c</string>"
xcontent = xcontent & "<string>d</string>"
xcontent = xcontent & "<string>e</string>"
xcontent = xcontent & "</ArrayOfString>"
Dim rdr As XmlReader = XmlReader.Create(New StringReader(xcontent))
Dim xdoc As XDocument = XDocument.Load(rdr)
Dim ele = xdoc.Elements("ArrayOfString")
Dim node1 = ele.Descendants("string").Where(Function(x) x.Value ="e").Select(Function(x) x)
node1.Remove()
End Sub
Result:
<ArrayOfString xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<string>a</string>
<string>b</string>
<string>c</string>
<string>d</string>
</ArrayOfString>