#!/bin/bash
user_download_dir_folder="12\"4'5"
user_download_dir_folder=$(tr -d \"\' <<< "$user_download_dir_folder")
echo "$user_download_dir_folder"

user_download_dir_folder="12\"4'5"
user_download_dir_folder="${user_download_dir_folder//[\"\']/}"
echo "$user_download_dir_folder"