diff --git a/api-ref/source/v3/parameters.yaml b/api-ref/source/v3/parameters.yaml
index f0344ade3f0..7256e9cdf62 100644
--- a/api-ref/source/v3/parameters.yaml
+++ b/api-ref/source/v3/parameters.yaml
@@ -2370,13 +2370,6 @@ size:
   in: body
   required: true
   type: integer
-skip_validation:
-  description: |
-    If set to false, the quota value can't be set lower than the in_use quota.
-    Default is True.
-  in: body
-  required: false
-  type: boolean
 snapshot:
   description: |
     A partial representation of a snapshot used in
diff --git a/api-ref/source/v3/quota-sets.inc b/api-ref/source/v3/quota-sets.inc
index 38b0aee62ce..9e27556f6b8 100644
--- a/api-ref/source/v3/quota-sets.inc
+++ b/api-ref/source/v3/quota-sets.inc
@@ -130,7 +130,6 @@ Request
    - gigabytes: gigabytes
    - gigabytes_{volume_type}: gigabytes_for_type
    - backup_gigabytes: backup_gigabytes
-   - skip_validation: skip_validation
 
 Request Example
 ---------------
diff --git a/api-ref/source/v3/samples/quotas-update-request.json b/api-ref/source/v3/samples/quotas-update-request.json
index 7f0234ab86f..9735bb3cae2 100644
--- a/api-ref/source/v3/samples/quotas-update-request.json
+++ b/api-ref/source/v3/samples/quotas-update-request.json
@@ -5,5 +5,4 @@
         "volumes_ceph": 3,
         "backups": 4
     },
-    "skip_validation": false
 }
diff --git a/cinder/api/contrib/quotas.py b/cinder/api/contrib/quotas.py
index ec4029e4ab5..f3268a97f58 100644
--- a/cinder/api/contrib/quotas.py
+++ b/cinder/api/contrib/quotas.py
@@ -211,21 +211,6 @@ class QuotaSetsController(wsgi.Controller):
 
         self.assert_valid_body(body, 'quota_set')
 
-        # TODO(wxy): Change "skip_validation"'s default value to  False in
-        # Queens.
-        # Get the optional argument 'skip_validation' from body,
-        # if skip_validation is False, then validate existing resource.
-        skip_flag = body.get('skip_validation', True)
-        if not strutils.is_valid_boolstr(skip_flag):
-            msg = _("Invalid value '%s' for skip_validation.") % skip_flag
-            raise exception.InvalidParameterValue(err=msg)
-        skip_flag = strutils.bool_from_string(skip_flag)
-        if skip_flag:
-            LOG.warning("It's unsafe to skip validating the existing "
-                        "resource's quota when updating it. Cinder will force "
-                        "validate it in Queens, please try to use "
-                        "skip_validation=False for quota updating now.")
-
         bad_keys = []
 
         # NOTE(ankit): Pass #1 - In this loop for body['quota_set'].items(),
@@ -280,10 +265,7 @@ class QuotaSetsController(wsgi.Controller):
                 body['quota_set'][key], key, min_value=-1,
                 max_value=db.MAX_INT)
 
-            # Can't skip the validation of nested quotas since it could mess up
-            # hierarchy if parent limit is less than childrens' current usage
-            if not skip_flag or use_nested_quotas:
-                self._validate_existing_resource(key, value, quota_values)
+            self._validate_existing_resource(key, value, quota_values)
 
             if use_nested_quotas:
                 try:
diff --git a/cinder/tests/unit/api/contrib/test_quotas.py b/cinder/tests/unit/api/contrib/test_quotas.py
index 2a0c5cb1639..8c9e279394b 100644
--- a/cinder/tests/unit/api/contrib/test_quotas.py
+++ b/cinder/tests/unit/api/contrib/test_quotas.py
@@ -309,33 +309,16 @@ class QuotaSetsControllerTest(QuotaSetsControllerTestBase):
                          db.quota_usage_get_all_by_project(ctxt,
                                                            fake.PROJECT_ID))
 
-    def test_update_lower_than_existing_resources_when_skip_false(self):
+    def test_update_lower_than_existing_resources(self):
         self._commit_quota_reservation()
-        body = {'quota_set': {'volumes': 0},
-                'skip_validation': 'false'}
+        body = {'quota_set': {'volumes': 0}}
         self.assertRaises(webob.exc.HTTPBadRequest, self.controller.update,
                           self.req, fake.PROJECT_ID, body)
         # Ensure that validation works even if some resources are valid
-        body = {'quota_set': {'gigabytes': 1, 'volumes': 10},
-                'skip_validation': 'false'}
+        body = {'quota_set': {'gigabytes': 1, 'volumes': 10}}
         self.assertRaises(webob.exc.HTTPBadRequest, self.controller.update,
                           self.req, fake.PROJECT_ID, body)
 
-    def test_update_lower_than_existing_resources_when_skip_true(self):
-        self._commit_quota_reservation()
-        body = {'quota_set': {'volumes': 0},
-                'skip_validation': 'true'}
-        result = self.controller.update(self.req, fake.PROJECT_ID, body)
-        self.assertEqual(body['quota_set']['volumes'],
-                         result['quota_set']['volumes'])
-
-    def test_update_lower_than_existing_resources_without_skip_argument(self):
-        self._commit_quota_reservation()
-        body = {'quota_set': {'volumes': 0}}
-        result = self.controller.update(self.req, fake.PROJECT_ID, body)
-        self.assertEqual(body['quota_set']['volumes'],
-                         result['quota_set']['volumes'])
-
     def test_delete(self):
         result_show = self.controller.show(self.req, fake.PROJECT_ID)
         self.assertDictEqual(make_body(), result_show)
diff --git a/releasenotes/notes/releasenotes/notes/bug-1735337-remove-skip-quota-validation-flag-2ecb24143f1f1292.yaml b/releasenotes/notes/releasenotes/notes/bug-1735337-remove-skip-quota-validation-flag-2ecb24143f1f1292.yaml
new file mode 100644
index 00000000000..8d928c22ef7
--- /dev/null
+++ b/releasenotes/notes/releasenotes/notes/bug-1735337-remove-skip-quota-validation-flag-2ecb24143f1f1292.yaml
@@ -0,0 +1,4 @@
+---
+fixes:
+  - Quota validations are now forced for all APIs. skip_validation flag is
+    now removed from the request body for the quota-set update API.