Cleaning up dummy data

Without context it is difficult to help.

If you are in development, and you are happy to clear everything from your database, then php artisan migrate:fresh will drop all your tables (and data) and re-run migrations - everything will be lost!

only the data and not the table.

For instance I am having a car table without any data. And I use factory to insert it with 100 dummy data. Now, I want to delete it all without deleting the table so it's ready to be inserted with a new data.

How to do this?

You can drop all data and reset the primary key without dropping the table using truncate() method, for example within php artisan tinker

Car::truncate();

otherwise, you could do this directly on your database using the command that is appropriate to your particular DBMS.