diff --git a/.circleci/config.yml b/.circleci/config.yml
index 549a8b57..3693ac0e 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -312,12 +312,6 @@ jobs:
       - attach_workspace:
           at: dist
 
-      - run:
-          name: install doxygen
-          command: |
-            sudo apt update
-            sudo apt install doxygen
-
       - run:
           name: install package and docs dependencies
           command: |
@@ -334,10 +328,10 @@ jobs:
               --only-binary :all:
 
       - run:
-          name: build docs
+          name: build docs with warnings as error
           command: |
             . env/bin/activate
-            make -C docs cpp html
+            make -C docs html SPHINXOPTS=-W
 
       - store_artifacts:
           path: docs/build/html
diff --git a/docs/Doxyfile b/docs/Doxyfile
deleted file mode 100644
index 395dd27e..00000000
--- a/docs/Doxyfile
+++ /dev/null
@@ -1,14 +0,0 @@
-# Doxyfile 1.9.1
-
-PROJECT_NAME           = dwave-optimization
-
-OUTPUT_DIRECTORY       = $(DOXYGEN_OUTPUT_DIRECTORY)
-INPUT                  = ../dwave/optimization/include/dwave-optimization/ \
-                         ../dwave/optimization/include/dwave-optimization/nodes/
-FILE_PATTERNS          = *.hpp
-
-GENERATE_HTML          = NO
-GENERATE_LATEX         = NO
-GENERATE_XML           = YES
-
-WARN_IF_UNDOCUMENTED   = NO
diff --git a/docs/Makefile b/docs/Makefile
index ae206153..075123b3 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -8,8 +8,6 @@ SPHINXPROJ    = dwave
 SOURCEDIR     = .
 BUILDDIR      = build
 
-DOXYGEN_OUTPUT_DIRECTORY=$(BUILDDIR)/doxygen/ 
-
 # Put it first so that "make" without argument is like "make help".
 help:
 	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
@@ -20,15 +18,6 @@ clean:
 	-rm -rf $(BUILDDIR)
 	-rm -rf reference/generated
 
-cpp:
-	# Note that sphinx's conf.py expects the build directory to be build/
-	# and unfortunately there isn't an easy way to read the BUILDDIR from the
-	# conf.py.
-	# We could do additional env variables, but this is mostly for the benefit
-	# of the SDK, so we'll leave it be for now.
-	mkdir $(BUILDDIR) -p
-	DOXYGEN_OUTPUT_DIRECTORY=$(DOXYGEN_OUTPUT_DIRECTORY) doxygen Doxyfile
-
 # Catch-all target: route all unknown targets to Sphinx using the new
 # "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
 %: Makefile
diff --git a/docs/conf.py b/docs/conf.py
index 38da8663..fcc13a42 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -3,9 +3,6 @@
 # For the full list of built-in configuration values, see the documentation:
 # https://www.sphinx-doc.org/en/master/usage/configuration.html
 
-import os
-import subprocess
-
 # -- Project information -----------------------------------------------------
 
 extensions = [
@@ -22,7 +19,6 @@
     'sphinx.ext.ifconfig',
 
     # other extensions
-    'breathe',
     'sphinx_design',
 ]
 
@@ -70,16 +66,6 @@
     'dwave.optimization.typing.ArraySymbolLike': 'ArraySymbol | numpy.typing.ArrayLike',
 }
 
-# -- Breathe --------------------------------------------------------------
-
-breathe_projects = {
-  'dwave-optimization': os.path.join(os.path.dirname(os.path.abspath(__file__)), 'build', 'doxygen', 'xml'),
-}
-
-# see https://breathe.readthedocs.io/en/latest/readthedocs.html
-if os.environ.get('READTHEDOCS', False):
-    subprocess.call('make cpp', shell=True, cwd=os.path.dirname(os.path.abspath(__file__)))
-
 # -- Options for HTML output ----------------------------------------------
 
 html_theme = "pydata_sphinx_theme"
diff --git a/docs/cpp.rst b/docs/cpp.rst
deleted file mode 100644
index 0e25d06e..00000000
--- a/docs/cpp.rst
+++ /dev/null
@@ -1,15 +0,0 @@
-:orphan:
-
-.. _optimization_cpp:
-
-=======
-C++ API
-=======
-
-dwave::optimization
--------------------
-
-.. doxygennamespace:: dwave::optimization
-    :project: dwave-optimization
-    :content-only:
-    :members:
diff --git a/docs/philosophy.rst b/docs/philosophy.rst
index d7f6bc79..0e10fd83 100644
--- a/docs/philosophy.rst
+++ b/docs/philosophy.rst
@@ -5,7 +5,7 @@ Philosophy
 ==========
 
 `dwave-optimization` and
-the `Leap <https://cloud.dwavesys.com/leap/>`_\ |TM| service's quantum-classical
+the `Leap <https://cloud.dwavesys.com/leap/>`_\ ™ service's quantum-classical
 hybrid nonlinear solver
 incorporate features and design principles from each of the following areas:
 
diff --git a/pyproject.toml b/pyproject.toml
index 9e81449e..f6908f75 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -110,7 +110,6 @@ docs = [
     "pydata-sphinx-theme==0.16.1",
     "sphinx==8.2.3",
     "sphinx-design==0.6.1",
-    "breathe==4.35.0",
 ]
 
 [tool.cibuildwheel]