DataGridView.ClearColumnFilter Method

Name	Parameters	Description
ClearColumnFilter(GridColumn)	column	Resets FilterString or FilterExpression applied to the column object passed in the method parameters. The method does not reset a filter set using the Auto Filter Row.
ClearColumnFilter(String)	fieldName	Resets FilterString or FilterExpression applied to the column. To specify the column, pass its underlying field’s name to the method parameters. The method does not reset a filter set using the Auto Filter Row.