How to reset a repository if gitignore didn't download initially?

Question

git

There is a repository that I cloned, but it clones without .gitingore.
After I cloned, I put 4 folders with pictures and videos in the folder.
After that, I noticed that there is no gitignore file and in my git status it gives out all the files that I uploaded (pictures, videos)
They sent me a customized gitignore file and I copied it to the project folder.
Question: How can I reset the repository so that the folders with pictures and videos are preserved, but the rules from gitignore are taken into account?

Answer 1

I put 4 folders with pictures and videos in the folder

committed?
then you add .gitignore
then git rm --cached afile.ext or git rm -rf --cached afolder
and commit again. the file will remain locally, it will not be included in the commit