BUG: fixes #53935 Categorical order lost after call to remove_categories

doc/source/whatsnew/v2.1.0.rst

@@ -371,6 +371,7 @@ Bug fixes
 
 Categorical
 ^^^^^^^^^^^
+- Bug in :meth:`CategoricalIndex.remove_categories` , with categories it now retains the original order when removing an element from the categories list(:issue:`53935`).
 - Bug in :meth:`Series.astype` with ``dtype="category"`` for nullable arrays with read-only null value masks (:issue:`53658`)
 - Bug in :meth:`Series.map` , where the value of the ``na_action`` parameter was not used if the series held a :class:`Categorical` (:issue:`22527`).
 -

pandas/core/indexes/base.py

@@ -3572,7 +3572,7 @@ def _intersection_via_get_indexer(
         return result
 
     @final
-    def difference(self, other, sort=None):
+    def difference(self, other, sort=False):
         """
         Return a new Index with elements of index not in `other`.
 

pandas/tests/indexes/categorical/test_category.py

@@ -373,3 +373,18 @@ def test_method_delegation(self):
         msg = "cannot use inplace with CategoricalIndex"
         with pytest.raises(ValueError, match=msg):
             ci.set_categories(list("cab"), inplace=True)
+
+    def test_remove_maintains_order(self):
+        ci = CategoricalIndex(list("abcdda"), categories=list("abcd"))
+        result = ci.reorder_categories(["d", "c", "b", "a"], ordered=True)
+        tm.assert_index_equal(
+            result,
+            CategoricalIndex(list("abcdda"), categories=list("dcba"), ordered=True),
+        )
+        result = result.remove_categories(["c"])
+        tm.assert_index_equal(
+            result,
+            CategoricalIndex(
+                ["a", "b", np.nan, "d", "d", "a"], categories=list("dba"), ordered=True
+            ),
+        )