Switch frappe from 7.2.30 to 7.2.19

Hi, @gvyshnya,

I have modified core ERPNext module not Frappe. I have modified accounting report like as balance sheet, general ledger etc. So if I get trouble for this then I want to install frappe 7.2.19 at my localhost. How is it possible.
If I install frappe then always installed frappe 7.2.30