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

search for grub

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b38e75-e69e.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b38e75-e69e.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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