OK I got it.
We need a component to manage sheet: delete, rename.
We need a workbook which can stay useable even when the file is saved. This way you could manipulate the file, save it, manipulate, save and so on...
I will fill theses gaps in the next 2 week (I hope ;-)
Here an idea with a tJavaRow component (assuming you have your sheet name to delete in the schema column sheet_name_to_delete. Probably change the component index for the tFileExcelWorkbookOpen.
org.apache.poi.ss.usermodel.Workbook workbook = (org.apache.poi.ss.usermodel.Workbook) globalMap.get("workbook_tFileExcelWorkbookOpen_1");
int sheetIndex = workbook.getSheetIndex(input_row.sheet_name_to_delete);
if (sheetIndex >= 0) {
workbook.removeSheetAt(sheetIndex);
}