git remove

git rm file1.txt
git commit -m "remove file1.txt"

But if you want to remove the file only from the Git repository and not remove it from the filesystem, use:
git rm --cached file1.txt
git rm -r --cached folder
git commit -m "remove file1.txt & folder"

https://stackoverflow.com/questions/2047465/how-can-i-delete-a-file-from-a-git-repository