WordPress DROP tables with prefix

Hi I am trying to drop some tables in bulk before creating them again for testing purposes.

I am trying to run this statement

dbDelta(       "SET GROUP_CONCAT_MAX_LEN=10000;       SET @tbls = (SELECT GROUP_CONCAT(TABLE_NAME)       FROM information_schema.TABLES       WHERE TABLE_SCHEMA = 'wp_test'       AND TABLE_NAME LIKE 'mch_%');       SET @delStmt = CONCAT('DROP TABLE ',  @tbls);       PREPARE stmt FROM @delStmt;       EXECUTE stmt;       DEALLOCATE PREPARE stmt;",       $  wpdb->prefix ) 

But nothing happens, my plugin gets activated with no errors, but the tables are still there.

I am new to this stuff, so I would like to understand the proper way to do this.