how can we can delete the previous output to see next output

Answer 1

Usually, the console was not designed to allow for that as its concept is that of a virtual teletype writer. Nevertheless, there are control chars in the ASCII charset that might work without using a library like curl. The carriage return char '\r' would be my best guess to try that (assuming you are not on Mac OS).

Answer 2

clrscr();

Answer 3

Use header file #include<conio> and then type clrscr() in the starting of body i.e when opening void main()