If you are willing to go back to version 3 after the update to WP Travel Version 4, you do not have to worry at all. You can go back to the previous version any time you like.
Note: This option is for the user who has updated the plugin from WP Travel V3 to WP Travel V4
For this you need to go to Admin Panel > WP Travel > Settings > General and disable the “Switch to V4” option.
Note: Switch to v4 option has also been removed since WP Travel v5.1.0. For detail, please refer to the knowledge Base.