Delete single row GSheet

With that version the script automatically uses the first sheet in the spreadsheet.

If you want to name the sheet then you need to change every instance of:

var sh = ss.getSheets()[0];

to

var sh = ss.getSheetByName(e.parameter.SH);

remembering to republish your web app to a new version

and send a parameter &SH=Sheetname from your app (Sheetname being what ever the name of your sheet is, e.g. Sheet1)

Alternatively, you may want to look at:

or