Having trouble removing files from git tracking

How do I reverse a git add, and untrack files on localhost

In my localhost version of mysite, I accidentally committed a folder called ‘core’.

Now I want to remove the files form commit and add, and untrack them.

I ran:

git reset HEAD core/

which put the files into status: ‘Unstaged changes after reset:’ and then the next:

git status

listed them as: “Changes not staged for commit:”

Now I want to un-add them and untrack them. I’d prefer to do the whole directory at once but so far I only know how to do each file one by one like this:

git rm --cached core/.jshintignore

The problem with that is I receive this message:

git status

Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)
	deleted: core/.jshintignore

What does “deleted” mean in the above context?

If I commit and push; and pull on my remote/live server will anything happen to that remote file?

What do I do to untrack and hide ‘core’ directory and all its subdirectories without deleting file or modifying the remote live server?

hoping someone may have some insight here?