How clear GridView in asp.net?

I resolved the problem, in the moment than clear the GridView with

DataTable ds = new DataTable();
ds = null;
grdResultados.DataSource = ds;
grdResultados.DataBind();

this clear the GridView but dont clear the names of columns, and this was the error, also have to clean the names of the columns. To remove the columns:

for (int i = 0; grdResultados.Columns.Count > i; )
{
    grdResultados.Columns.RemoveAt(i);
}

and in the method of load th GridView must be generate the columns automatically with this property:

grdResultados.AutoGenerateColumns = true;

I leave this in case anyone else has the same problem

Just use null value:

grdResultados.DataSource = null;
grdResultados.DataBind();

try this

grdResultados.DataSource = null;

or

grdResultados.Rows.Clear();

then rebind the gridview

int gvHasRows = grdResultados.Rows.Count;
if (gvHasRows > 0)
{
    grdResultados.Columns.Clear();
    grdResultados.DataBind();
}

First check that there is data in the Gridview before trying to clear. Rows has no Clear function.