Delete, Truncate or Drop to clean out a table in MySQL

   Drop will do just that....drop the table in question, unless the table is a parent to another table.

   Delete will remove all the data that meets the condition; if no condition is specified, it'll remove all the data in the table.
   Truncate is similar to delete; however, it resets the auto_increment counter back to 1 (or the initial starting value). However, it's better to use truncate over delete because delete removes the data by each row, thus having a performance hit than truncate. However, truncate will not work on InnoDB tables where referential integrity is enforced unless it is turned off before the truncate command is issued.
   So, relax; unless you issue a drop command on the table, it won't be dropped.

TRUNCATE will reset your auto-increment seed (on InnoDB tables, at least), although you could note its value before truncating and re-set accordingly afterwards using alter table:

ALTER TABLE t2 AUTO_INCREMENT = value

drop table will remove the entire table with data

delete * from table will remove the data, leaving the autoincrement values alone. it also takes a while if there's a lot of data in the table.

truncate table will remove the data, reset the autoincrement values (but leave them as autoincrement columns, so it'll just start at 1 and go up from there again), and is very quick.