Hi Juan,
You may use the ExtensionFeedItemService to update the AdSchedule or remove the existing schedules. You will need to make a request with the ExtensionFeedItem and resource name of the specific feed item. Please find the code sample below in Java as a reference.
ExtensionFeedItem extensionFeedItem = ExtensionFeedItem.newBuilder()
.setResourceName(ResourceNames.extensionFeedItem(customerId, 93452085881L))
.setStartDateTime(StringValue.of("2018-02-01 14:34:30"))
.setDevice(FeedItemTargetDevice.MOBILE)
.setEndDateTime(StringValue.of("2018-02-01 14:34:30"))
.setStatus(FeedItemStatus.ENABLED)
.build();
ExtensionFeedItemOperation operation = ExtensionFeedItemOperation.newBuilder()
.setUpdate(extensionFeedItem)
.setUpdateMask(FieldMasks.allSetFieldsOf(extensionFeedItem))
.build();
Please give this a try and let me know if you have any issues.
Thanks,
Bharani, Google Ads API Team