Either configure Virtual Box shortcut keys, or use command
clear in terminal.
Edit (or elaboration): The shortcut which I was using to clear the screen was
Right Ctrl + L, but
Right Ctrl key is by default the Host Key for Virtual Box, that's why it was clearing the screen, in fact, it was giving me some other Virtual Box options. Now if I press
Left Ctrl + L, I am able to clear the screen.
But if you don't want to use
Left Ctrl key, you can configure your Host Key and other type of shortcut keys according to your preferences by going to Virtual Box's
File -> Preferences -> Input -> Virtual Machine option .
I changed my host key to Right Shift which I rarely use for normal shortcuts.