I want to keep only zorin os in my PC but I have a doubt If I use Local disk C for zorin os installation. it will delete only local disk C data or entire data either in Local disk D or E plz give me answer
It will only delete the drive you select for installation, the other drives will not be touched.
Keep in mind that the hard drive naming convention of "C", "D", "E"... does not exist on Linux. So you may want to unplug those other drives just in case as to not accidentally install ZorinOS in the wrong drive.
Like zenzen said. Even on Windows, unplug old drives ( I did not and grub loader installed on my mechanical drive )