diff --git a/news/698.api_change b/news/698.api_change
new file mode 100644
index 000000000..3a13562b1
--- /dev/null
+++ b/news/698.api_change
@@ -0,0 +1 @@
+Removed support for `OmegaConf.is_optional()`.
diff --git a/omegaconf/omegaconf.py b/omegaconf/omegaconf.py
index d23b2b15b..5c6ec5e83 100644
--- a/omegaconf/omegaconf.py
+++ b/omegaconf/omegaconf.py
@@ -612,21 +612,6 @@ def is_missing(cfg: Any, key: DictKeyType) -> bool:
         except (UnsupportedInterpolationType, KeyError, AttributeError):
             return False
 
-    # DEPRECATED: remove in 2.2
-    @staticmethod
-    def is_optional(obj: Any, key: Optional[Union[int, str]] = None) -> bool:
-        warnings.warn(
-            "`OmegaConf.is_optional()` is deprecated, see https://github.com/omry/omegaconf/issues/698",
-            stacklevel=2,
-        )
-        if key is not None:
-            assert isinstance(obj, Container)
-            obj = obj._get_node(key)
-        if isinstance(obj, Node):
-            return obj._is_optional()
-        else:
-            return True
-
     # DEPRECATED: remove in 2.2
     @staticmethod
     def is_none(obj: Any, key: Optional[Union[int, DictKeyType]] = None) -> bool:
diff --git a/tests/test_omegaconf.py b/tests/test_omegaconf.py
index 4a3517eea..dd4ce43ee 100644
--- a/tests/test_omegaconf.py
+++ b/tests/test_omegaconf.py
@@ -1,6 +1,5 @@
 import pathlib
 import platform
-import re
 from pathlib import Path
 from typing import Any
 
@@ -227,21 +226,6 @@ def test_is_dict(cfg: Any, expected: bool) -> None:
     assert OmegaConf.is_dict(cfg) == expected
 
 
-def test_is_optional_deprecation() -> None:
-    with warns(UserWarning, match=re.escape("`OmegaConf.is_optional()` is deprecated")):
-        OmegaConf.is_optional("xxx")
-
-
-def test_coverage_for_deprecated_OmegaConf_is_optional() -> None:
-    cfg = OmegaConf.create({"node": 123})
-    with warns(UserWarning):
-        assert OmegaConf.is_optional(cfg)
-    with warns(UserWarning):
-        assert OmegaConf.is_optional(cfg, "node")
-    with warns(UserWarning):
-        assert OmegaConf.is_optional("not_a_node")
-
-
 @mark.parametrize("is_none", [True, False])
 @mark.parametrize(
     "fac",