firebase reset password without sending reset password email in Reactjs ?

You can use the updatePassword method that comes with firebase.

import { getAuth, updatePassword } from "firebase/auth";

const auth = getAuth();

const user = auth.currentUser;
const newPassword = getPWFromForm();

updatePassword(user, newPassword).then(() => {
  // Update successful.
}).catch((error) => {
  // An error ocurred
  // ...
});