TYPO3.Flow

Maybe its a solution to remove them by filter?
Example from my project how to use a filter on a doctrine collection (see @todo inline comment):

<?php

    class AbstractProduct{

        /**
         * @var \Doctrine\Common\Collections\Collection<\BLEICKER\I18n\Domain\Model\PropertyTranslation>
         * @ORM\ManyToMany(cascade={"persist", "detach", "merge"})
         * @ORM\OrderBy({"propertyName" = "ASC"})
         */
        protected $propertyTranslations;

        /**
         * @return void
         */
        public function __construct() {
            $this->propertyTranslations = new \Doctrine\Common\Collections\ArrayCollection();
        }

        /**
         * @return PropertyTranslation
         * @return $this
         */
        public function removePropertyTranslation(PropertyTranslation $propertyTranslation) {
            $filter = function (PropertyTranslation $existingTranslation) use ($propertyTranslation) {
                // @todo At this point you could use persistenceManager to check for equal identities
                return ($existingTranslation->getLocale() === $propertyTranslation->getLocale() && $existingTranslation->getPropertyName() === $propertyTranslation->getPropertyName());
            };

            $existingTranslationToRemove = $this->propertyTranslations->filter($filter);

            while ($existingTranslationToRemove->current()) {
                $this->propertyTranslations->removeElement($existingTranslationToRemove->current());
                $existingTranslationToRemove->next();
            }

            return $this;
        }
    }

?>

Just a little reminder (for all major candidates for Flow 3.0): Feature Freeze is in 10 days! Let me know if you need any help with this.