docs: remove delete partition segment from preview section

Author: TomMalow

README.md

@@ -249,40 +249,6 @@ az cosmosdb update  --resource-group $ResourceGroup --name $AccountName --enable
 
 See [MS Learn](https://learn.microsoft.com/en-us/azure/cosmos-db/priority-based-execution) for more details.
 
-### Delete resources by partition key
-
-The preview version of the library extends the `ICosmosWriter` and `ILowPriorityCosmosWriter` with and additional method `DeletePartitionAsync` to delete all resources in a container based on a partition key. The deletion will be executed in a CosmosDB background service using a percentage of the RU's available. The effect are available immediatly as all resources in the partition will not be available through reads or queries.
-
-In order to use this new method the "Delete All Items By Partition Key" feature needs to be enabled on the CosmosDB account. 
-
-This can be done through Azure CLI:
-
-```bash
-# Delete All Items By Partition Key
-az cosmosdb update  --resource-group $ResourceGroup --name $AccountName --capabilities DeleteAllItemsByPartitionKey
-```
-
-or wih bicep:
-
-```bicep
-resource cosmosAccount 'Microsoft.DocumentDB/databaseAccounts@2024-05-15' = {
-  name: cosmosName
-  properties: {
-    databaseAccountOfferType: 'Standard'
-    locations: location
-    capabilities: [
-      {
-        name: 'DeleteAllItemsByPartitionKey'
-      }
-    ]
-  }
-}
-```
-
-If the feature is not enabled when calling this method then a `CosmosException` will be thrown.
-
-See [MS Learn](https://learn.microsoft.com/en-us/azure/cosmos-db/nosql/how-to-delete-by-partition-key) for more details.
-
 ## Unit Testing
 The reader and writer interfaces can easily be mocked, but in some cases it is nice to have a fake version of a reader or writer to mimic the behavior of the read and write operations. For this purpose the `Atc.Cosmos.Testing` namespace contains the following fakes:
 

test/Atc.Cosmos.Tests/CosmosWriterTests.cs

@@ -306,7 +306,11 @@ public async Task DeletePartitionAsync_Calls_DeleteAllItemsByPartitionKeyStreamA
                 .Received(1)
                 .DeleteAllItemsByPartitionKeyStreamAsync(
                     new PartitionKey(record.Pk),
+#if PREVIEW
                     Arg.Is<ItemRequestOptions>(o => o.PriorityLevel == PriorityLevel.High),
+#else
+                    Arg.Any<ItemRequestOptions>(),
+#endif
                     cancellationToken: cancellationToken);
         }