How to verify whether the windows system is installed under Centos?

there is a Thinkpad notebook with a label Windows 8 pro, at the bottom. At present, the boot automatically enters the Centos system. How to verify whether there is a Windows system? from the boot boot point of view, you can only choose different kernel versions of Centos to boot. Does it mean that this computer no longer has a Windows system?
in addition, I can only log in with one of the users (I don"t know the password of the root user, but I can use the su command under the logged-in user). There is only 20 gigabytes of space left, which is very embarrassing (I was going to install a virtual machine).

Mar.05,2021

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