First, reset any changes
This will undo any changes you’ve made to tracked files and restore deleted files:
git reset HEAD --hard
Second, remove new files
This will delete any new files that were added since the last commit:
git clean -fd
Files that are not tracked due to .gitignore are preserved; they will not be removed
Warning: using -x instead of -fd would delete ignored files. You probably don’t want to do this.