It's not possible to remove indexes
<p>The following create statement shows the current structure of one of my MariaDB tables. </p>

<pre><code>CREATE TABLE `councilor` (
    `id` BIGINT(20) NOT NULL AUTO_INCREMENT,
    `user` BIGINT(20) NOT NULL,
    `council` INT(11) NOT NULL,
    `role` CHAR(50) NOT NULL DEFAULT 'member' COLLATE 'utf8_persian_ci',
    `cDate` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
    `uDate` TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP,
    `startDate` DATETIME NULL DEFAULT NULL,
    `endDate` DATETIME NULL DEFAULT NULL,
    `responsibility` VARCHAR(255) NULL DEFAULT NULL COLLATE 'utf8_persian_ci',
    `details` TEXT NULL COLLATE 'utf8_persian_ci',
    PRIMARY KEY (`id`),
    UNIQUE INDEX `userId_councilId` (`user`, `council`),
    INDEX `council_user_council_foreign` (`council`)
)
COLLATE='utf8_persian_ci'
ENGINE=InnoDB
ROW_FORMAT=COMPACT
AUTO_INCREMENT=11;
</code></pre>

<p>I need to remove the unique index, however trying to delete either of two keys fails. </p>

<pre><code>ALTER TABLE `councilor`
    DROP INDEX `userId_councilId`;
</code></pre>

<p>/* SQL Error (1553): Cannot drop index 'userId_councilId': needed in a foreign key constraint */</p>

<pre><code>ALTER TABLE `councilor`
    DROP INDEX `council_user_council_foreign`;
</code></pre>

<p>/* SQL Error (1553): Cannot drop index 'council_user_council_foreign': needed in a foreign key constraint */</p>

<p>Removing all table's rows does not help as well. However, if a new table is created by the above script the issue will not occur. </p>