Improve generate() API build instructions

docs/genai/howto/build-from-source.md

@@ -117,29 +117,6 @@ These instructions assume you already have CUDA installed.
 cd ..
 python build.py --cuda_home <path to cuda home> [--ort_home <ORT_HOME>]
 ```
-
-### Build for DirectML
-
-Two extra files are required for the DirectML build of onnxruntime-genai `dml_provider_factory.h` and `DirectML.dll`. 
-
-```cmd
-cd <ORT_HOME>
-curl -L https://github.com/microsoft/onnxruntime/releases/download/v1.17.1/Microsoft.ML.OnnxRuntime.DirectML.1.17.1.zip > Microsoft.ML.OnnxRuntime.DirectML.1.17.1.zip
-mkdir Microsoft.ML.OnnxRuntime.DirectML.1.17.1
-tar xvf Microsoft.ML.OnnxRuntime.DirectML.1.17.1.zip -C Microsoft.ML.OnnxRuntime.DirectML.1.17.1
-copy Microsoft.ML.OnnxRuntime.DirectML.1.17.1\build\native\include\dml_provider_factory.h include
-curl -L https://www.nuget.org/api/v2/package/Microsoft.AI.DirectML/1.13.1 > Microsoft.AI.DirectML.1.13.1.nupkg
-mkdir Microsoft.AI.DirectML.1.13.1
-tar xvf Microsoft.AI.DirectML.1.13.1.nupkg -C Microsoft.AI.DirectML.1.13.1
-copy Microsoft.AI.DirectML.1.13.1\bin\x64-win\DirectML.dll lib
-```
-
-After the extra files have been copied into <ORT HOME>, build onnxruntime-genai as follows:
-
-```bash
-python build.py --use_dml [--ort_home <ORT_HOME>]
-```
-
 
 ### Install the library into your application