Fehler beim Löschen des Gutschein

Hallo, ich habe ein Plugin für Neukunden-Rabatt installiert, aber da es nicht so war wie ich es mir vorgestellt habe gelöscht. Wollte auch unter „Marketing/Gutscheine“ das Gutschein entfernen - es geht nicht.
Kommt dieser fehlermeldung:

503 - Service Unavailable

Ups! Ein Fehler ist aufgetreten! Die nachfolgenden Hinweise sollten Ihnen weiterhelfen.
An exception occurred while executing ‚SELECT s0_.id AS id_0, s0_.description AS description_1,
s0_.vouchercode AS vouchercode_2, s0_.numberofunits AS numberofunits_3, s0_.value AS value_4,
s0_.minimumcharge AS minimumcharge_5, s0_.shippingfree AS shippingfree_6, s0_.bindtosupplier AS bindtosupplier_7,
s0_.valid_from AS valid_from_8, s0_.valid_to AS valid_to_9, s0_.ordercode AS ordercode_10, s0_.modus AS modus_11,
s0_.percental AS percental_12, s0_.numorder AS numorder_13, s0_.customergroup AS customergroup_14, s0_.restrictarticles AS restrictarticles_15,
s0_.strict AS strict_16, s0_.subshopID AS subshopID_17, s0_.taxconfig AS taxconfig_18, s0_.customer_stream_ids AS customer_stream_ids_19, s1_.id AS id_20,
s1_.voucherID AS voucherID_21, s1_.newcustomer AS newcustomer_22, s1_.voucherID AS voucherID_23 FROM s_emarketing_vouchers s0_ LEFT JOIN s_emarketing_vouchers_attributes s1_ ON s0_.id = s1_.voucherID WHERE s0_.id = ?‘ with params [2]: SQLSTATE[42S22]: Column not found: 1054 Unknown column ‚s1_.newcustomer‘ in ‚field list‘ in vendor/doctrine/dbal/lib/Doctrine/DBAL/DBALException.php on line 179 Stack trace: #0 vendor/doctrine/dbal/lib/Doctrine/DBAL/DBALException.php(150): Doctrine\DBAL\DBALException::wrapException(Object(Doctrine\DBAL\Driver\PDOMySql\Driver), Object(PDOException), ‚An exception oc…‘) #1 vendor/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(915): Doctrine\DBAL\DBALException::driverExceptionDuringQuery(Object(Doctrine\DBAL\Driver\PDOMySql\Driver), Object(PDOException), ‚SELECT s0_.id A…‘, Array) #2 vendor/doctrine/orm/lib/Doctrine/ORM/Query/Exec/SingleSelectExecutor.php(50): Doctrine\DBAL\Connection->executeQuery(‚SELECT s0_.id A…‘, Array, Array, NULL) #3 vendor/doctrine/orm/lib/Doctrine/ORM/Query.php(337): Doctrine\ORM\Query\Exec\SingleSelectExecutor->execute(Object(Doctrine\DBAL\Connection), Array, Array) #4 vendor/doctrine/orm/lib/Doctrine/ORM/AbstractQuery.php(968):
Doctrine\ORM\Query->_doExecute() #5 vendor/doctrine/orm/lib/Doctrine/ORM/AbstractQuery.php(923): Doctrine\ORM\AbstractQuery->executeIgnoreQueryCache(NULL, 1) #6 vendor/doctrine/orm/lib/Doctrine/ORM/AbstractQuery.php(765): Doctrine\ORM\AbstractQuery->execute(NULL, 1) #7 engine/Shopware/Controllers/Backend/Voucher.php(262): Doctrine\ORM\AbstractQuery->getOneOrNullResult(1) #8 engine/Library/Enlight/Controller/Action.php(192): Shopware_Controllers_Backend_Voucher->getVoucherDetailAction() #9 engine/Library/Enlight/Controller/Dispatcher/Default.php(478): Enlight_Controller_Action->dispatch(‚getVoucherDetai…‘) #10 engine/Library/Enlight/Controller/Front.php(228): Enlight_Controller_Dispatcher_Default->dispatch(Object(Enlight_Controller_Request_RequestHttp), Object(Enlight_Controller_Response_ResponseHttp)) #11 engine/Shopware/Kernel.php(188): Enlight_Controller_Front->dispatch() #12 vendor/symfony/http-kernel/HttpCache/SubRequestHandler.php(102): Shopware\Kernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #13 vendor/symfony/http-kernel/HttpCache/HttpCache.php(453): Symfony\Component\HttpKernel\HttpCache\SubRequestHandler::handle(Object(Shopware\Kernel),
Object(Symfony\Component\HttpFoundation\Request), 1, true) #14 engine/Shopware/Components/HttpCache/AppCache.php(261):
Symfony\Component\HttpKernel\HttpCache\HttpCache->forward(Object(Symfony\Component\HttpFoundation\Request), true, NULL) #15 vendor/symfony/http-kernel/HttpCache/HttpCache.php(238):
Shopware\Components\HttpCache\AppCache->forward(Object(Symfony\Component\HttpFoundation\Request), true) #16 engine/Shopware/Components/HttpCache/AppCache.php(102): Symfony\Component\HttpKernel\HttpCache\HttpCache->pass(Object(Symfony\Component\HttpFoundation\Request), true) #17 shopware.php(122): Shopware\Components\HttpCache\AppCache->handle(Object(Symfony\Component\HttpFoundation\Request)) #18 {main}  

Kann mir jemanden weiterhelfen, wie ich die Gutscheine löschen kann?
DANKESCHÖN!

Mal den kompletten Cache gelöscht?