Drop is DDL statement.
The SQL DROP TABLE statement is used to remove a table definition and all data, indexes, triggers, constraints, and permission specifications for that table.
Caution : You have to be careful while using this command because once a table is deleted then all the information available in the table would also be lost forever.
Syntax :
1) For Drop table :
DROP TABLE table_name;
2) For Index :
DROP INDEX index_name;
3) For Database :
DROP DATABASE database_name;