Auto increment values are always incrementing, as the name already indicates. It's usually a good thing to keep that to ensure you don't run into conflicts with existing data, but sometimes, maybe while you're working in a development environment, you want to keep your tables small to have a good overview and not get lost in millions of rows.
You can easily remove all rows using
DELETE FROM your_table, but that will not reset the auto increment value.
If you already ran your
DELETE FROM query, you can easily set the next auto increment value using this query:
ALTER TABLE your_table AUTO_INCREMENT=1;
If you're clearing the whole table, you can also run this query using the DDL command
TRUNCATE TABLE your_table
This will remove the data from your table and also reset the auto increment value.