diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0d336cd..0987240 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,9 @@ Previous classification is not required if changes are simple or all belong to t
 ### Major Changes
 
 - In interface type `IChatHistoryProvider` added new method `DeleteChatMessagesHistoryAsync` to delete a user's chat history messages. This method is implemented in `ChatHistoryProvider`.
+- Added new interface `Encamina.Enmarcha.AI.Abstractions.ISemanticTextSplitter` and its implementations `Encamina.Enmarcha.AI.SemanticTextSplitter` to split a text into meaningful chunks based on embeddings.
+- Added a new utility class for mathematical operations `Encamina.Enmarcha.Core.MathUtils`.
+- Fixed `DeleteAsync<TEntityId>` method in `CosmosRepository<T>`. This method was always throwing exceptions because the partition key value was always `null`. It is fixed by considering the `Id` to delete the whole partition. If a specific item in the partition should be removed, then use the `DeleteAsync` on-generic method.
 - Updated dependencies:
   - Updated `Bogus` from `35.4.0` to `35.4.1`.
   - Updated `Azure.Core` from `1.37.0` to `1.38.0`.
@@ -50,8 +53,6 @@ Previous classification is not required if changes are simple or all belong to t
   - Updated `xunit.analyzers` from `1.10.0` to `1.11.0`.
   - Updated `xunit.extensibility.core` from `2.6.6` to `2.7.0`.
   - Updated `xunit.runner.visualstudio` from `2.5.6` to `2.5.7`.
-- Added new interface `Encamina.Enmarcha.AI.Abstractions.ISemanticTextSplitter` and its implementations `Encamina.Enmarcha.AI.SemanticTextSplitter` to split a text into meaningful chunks based on embeddings.
-- Added a new utility class for mathematical operations `Encamina.Enmarcha.Core.MathUtils`.
 
 ### Minor Changes
 
diff --git a/Directory.Build.props b/Directory.Build.props
index fc7fbc0..bc923c3 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -17,7 +17,7 @@
 
   <PropertyGroup>
     <VersionPrefix>8.1.5</VersionPrefix>
-    <VersionSuffix>preview-05</VersionSuffix>
+    <VersionSuffix>preview-06</VersionSuffix>
   </PropertyGroup>
 
   <!--
diff --git a/src/Encamina.Enmarcha.Data.Cosmos/CosmosRepository{T}.cs b/src/Encamina.Enmarcha.Data.Cosmos/CosmosRepository{T}.cs
index edfb7f5..73e4706 100644
--- a/src/Encamina.Enmarcha.Data.Cosmos/CosmosRepository{T}.cs
+++ b/src/Encamina.Enmarcha.Data.Cosmos/CosmosRepository{T}.cs
@@ -3,6 +3,7 @@
 using System.Net;
 
 using Encamina.Enmarcha.Core.Extensions;
+using Encamina.Enmarcha.Entities.Abstractions;
 
 using Microsoft.Azure.Cosmos;
 using Microsoft.Azure.Cosmos.Linq;
@@ -317,7 +318,26 @@ public async Task<IQueryable<T>> GetAllAsync([NotNull] Func<IQueryable<T>, IQuer
     public async Task AddBatchAsync(IEnumerable<T> entities, CancellationToken cancellationToken) => await AddOrUpdateBulkAsync(entities, cancellationToken);
 
     /// <inheritdoc/>
-    public async Task DeleteAsync<TEntityId>(TEntityId id, CancellationToken cancellationToken) => await DeleteAsync(id is string idString ? idString : id.ToString(), null, cancellationToken);
+    /// <remarks>
+    /// From the point of view of Cosmos DB, the <paramref name="id"/> is the partition key value.
+    /// </remarks>
+    public async Task DeleteAsync<TEntityId>(TEntityId id, CancellationToken cancellationToken)
+    {
+        var partitionKey = GeneratePartition(id is string idString ? idString : id.ToString());
+
+        var resultSet = container.GetItemQueryIterator<CosmosDbItem>(new QueryDefinition(@"SELECT c.id FROM c"), requestOptions: new QueryRequestOptions()
+        {
+            PartitionKey = partitionKey,
+        });
+
+        while (resultSet.HasMoreResults)
+        {
+            foreach (var item in await resultSet.ReadNextAsync(cancellationToken))
+            {
+                await container.DeleteItemAsync<CosmosDbItem>(item.Id, partitionKey, cancellationToken: cancellationToken);
+            }
+        }
+    }
 
     private static async Task<(IQueryable<TEntity> Results, string ContinuationToken)> BuildResult<TEntity>(FeedIterator<TEntity> feedIterator, CancellationToken cancellationToken)
     {
@@ -342,6 +362,15 @@ public async Task<IQueryable<T>> GetAllAsync([NotNull] Func<IQueryable<T>, IQuer
 
     private static PartitionKey GeneratePartition(string partitionKey)
     {
-        return string.IsNullOrWhiteSpace(partitionKey) ? default : new PartitionKey(partitionKey);
+        return string.IsNullOrWhiteSpace(partitionKey)
+            ? throw new ArgumentNullException(nameof(partitionKey))
+            : new PartitionKey(partitionKey);
+    }
+
+    /// <summary>
+    /// Auxiliary type to retrieve items from Cosmos DB with just the unique identifier.
+    /// </summary>
+    private sealed class CosmosDbItem : IdentifiableBase<string>
+    {
     }
 }
diff --git a/src/Encamina.Enmarcha.SemanticKernel.Plugins.Chat/ChatHistoryProvider.cs b/src/Encamina.Enmarcha.SemanticKernel.Plugins.Chat/ChatHistoryProvider.cs
index 56f6673..d080479 100644
--- a/src/Encamina.Enmarcha.SemanticKernel.Plugins.Chat/ChatHistoryProvider.cs
+++ b/src/Encamina.Enmarcha.SemanticKernel.Plugins.Chat/ChatHistoryProvider.cs
@@ -34,9 +34,9 @@ public ChatHistoryProvider(Func<string, int> tokensLengthFunction, IAsyncReposit
     }
 
     /// <inheritdoc/>
-    public async Task DeleteChatMessagesHistoryAsync(string userId, CancellationToken cancellationToken)
+    public Task DeleteChatMessagesHistoryAsync(string userId, CancellationToken cancellationToken)
     {
-        await chatMessagesHistoryRepository.DeleteAsync(userId, cancellationToken);
+        return chatMessagesHistoryRepository.DeleteAsync(userId, cancellationToken);
     }
 
     /// <inheritdoc/>