Syntax:
DROP TABLESPACE tablespace_name
    [ENGINE [=] engine_name]

This statement drops a tablespace that was previously created using
CREATE TABLESPACE. It is supported with all MySQL NDB Cluster 7.5
releases, and with InnoDB in the standard MySQL Server as well.

ENGINE sets the storage engine that uses the tablespace, where
engine_name is the name of the storage engine. Currently, the values
InnoDB and NDB are supported. If not set, the value of
default_storage_engine is used. If it is not the same as the storage
engine used to create the tablespace, the DROP TABLESPACE statement
fails.

For an InnoDB tablespace, all tables must be dropped from the
tablespace prior to a DROP TABLESPACE operation. If the tablespace is
not empty, DROP TABLESPACE returns an error.

As with the InnoDB system tablespace, truncating or dropping InnoDB
tables stored in a general tablespace creates free space in the
tablespace .ibd data file, which can only be used for new InnoDB data.
Space is not released back to the operating system by such operations
as it is for file-per-table tablespaces.

An NDB tablespace to be dropped must not contain any data files; in
other words, before you can drop an NDB tablespace, you must first drop
each of its data files using ALTER TABLESPACE ... DROP DATAFILE.

Notes

o Tablespaces are not deleted automatically. A tablespace must be
  dropped explicitly using DROP TABLESPACE. DROP DATABASE has no effect
  in this regard, even if the operation drops all tables belonging to
  the tablespace.

o A DROP DATABASE operation can drop tables that belong to a general
  tablespace but it cannot drop the tablespace, even if the operation
  drops all tables that belong to the tablespace. The tablespace must
  be dropped explicitly using DROP TABLESPACE tablespace_name.

o Similar to the system tablespace, truncating or dropping tables
  stored in a general tablespace creates free space internally in the
  general tablespace .ibd data file which can only be used for new
  InnoDB data. Space is not released back to the operating system as it
  is for file-per-table tablespaces.

InnoDB Example

This example demonstrates how to drop an InnoDB general tablespace. The
general tablespace ts1 is created with a single table. Before dropping
the tablespace, the table must be dropped.

mysql> CREATE TABLESPACE `ts1` ADD DATAFILE 'ts1.ibd' Engine=InnoDB;

mysql> CREATE TABLE t1 (c1 INT PRIMARY KEY) TABLESPACE ts1 Engine=InnoDB;

mysql> DROP TABLE t1;

mysql> DROP TABLESPACE ts1;

NDB Example

This example shows how to drop an NDB tablespace myts having a data
file named mydata-1.dat after first creating the tablespace, and
assumes the existence of a log file group named mylg (see [HELP CREATE
LOGFILE GROUP]).

mysql> CREATE TABLESPACE myts
    ->     ADD DATAFILE 'mydata-1.dat'
    ->     USE LOGFILE GROUP mylg
    ->     ENGINE=NDB;

You must remove all data files from the tablespace using ALTER
TABLESPACE, as shown here, before it can be dropped:

mysql> ALTER TABLESPACE myts
    ->     DROP DATAFILE 'mydata-1.dat'
    ->     ENGINE=NDB;

mysql> DROP TABLESPACE myts;

URL: https://dev.mysql.com/doc/refman/5.7/en/drop-tablespace.html

