The following example clears contents of column three in the range B5:F19

Workbook.Sheets[1].UsedRange.Columns[1].Font.Bold := true;

Workbook.Sheets[1].Range['B5','F19'].Columns[3].ClearContents;

Workbook.Sheets[1].RCRange[2, 2, 5, 3].Columns[1].Merge(False);