src/TableBlueprint.php
public function dropIndex(array $columns): self
    {
        return $this->addOperation(
            new Operation\Index\Drop($this->table, $columns)
        );
    }
public function dropIndex(array $columns): self
    {
        return $this->addOperation(
            new Operation\Index\Drop($this->table, $columns)
        );
    }
Example:
$table->dropIndex(['email']);

@param array $columns
@return TableBlueprint