Error after deactivating WP Super Cache

Hi,
I have deactivated and deleted your plugin but I got an email with this error message:

Dear User,
WP Super Cache has been removed or deactivated from your blog but some files can not
be deleted.

(a link came up here, I didn't post it because I don't know if it can be done and if it's safe to do so)

You should delete these files manually.
You may need to change the permissions of the files or the parent directory.
You can read more about this in the Codex at
https://codex.www.ads-software.com/Changing_File_Permissions#About_Chmod
Thank you.

I am very inexperienced and have no idea what happened or how to proceed.

Please, can you help me?

Thank you in advance!