virtualbox – The terminal can not be deleted using `Ctrl + L` in the guest operating system

Therefore, I am using the XUbuntu version 18.04, within Oracle Virtual Box 5.2.18. Now every time I press Ctrl + L, it gives me a quick indication that it is going to change to the mode without problems, but I want my terminal to be erased. Some help? I am using Windows 10 as my host operating system.

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