remover elemento de un array por su indice

Dim index_remove As Integer = 3

array = array.Where(Function(x, index) index <> index_remove).ToArray

fuente

Remover el último caracter de un string

Dim inf As String="1,2,3,"

inf = inf.Remove(inf.Length - 1)
inf = "1,2,3"

fuente

Remover caracter

Dim x As String = "casa-arbol"
x = x.Remove(4, 1)

x  = "casaarbol"