What should I do if the previous system remains on the d disk after the dual system is reinstalled to the C disk?

What should I do if the previous system remains on the d disk after the dual system is reinstalled to the C disk? Linux general technology-Linux technology and application information. The following is a detailed description. My computer was originally installed with a Chinese version of xp and an English version of xp, respectively in disk C and disk D
Today, we installed ubuntu with the remaining space on the G Drive Using wubi.
Everything went well. Later, I went in and played casually. I saw a WINXP file.
If you don't know what it is, open it and a lot of files will pop up.
I don't know what it is, so I just deleted it all. I think it's impossible for ubuntu to influence the XP system.
After the restart, the system prompts NTLDR is missing. I think all the system files have been deleted.
After I copied the ntldr file from another computer, I also indicated that other system files were missing.
Later, I reinstalled the system to drive C.

Now the problem is that the space used by disk D is more than a dozen GB for no reason.
Could you tell me how to deal with it? I also deleted the folder in the unubtu on the G disk.
Why?

Thank you!