As far as I know, You will not require those turtlebot3_xxxxx packages.
I have completed the course and the project - so I am telling you from my experience!
In case you have any of those packages in your catkin_ws/src directory [ROS1] or ros2_ws/src directory [ROS2], you can safely delete those packages. You will never need them.
PS: In case you really want those files, you can download all your current project files from the IDE and then delete the rosject and get a new copy of the same rosject and upload your project files back into the new rosject. But, I really doubt if you would need this step.