diff --git a/admin.yaml b/admin.yaml
index d1817fc5a..a05c5a7fa 100644
--- a/admin.yaml
+++ b/admin.yaml
@@ -1704,14 +1704,15 @@ components:
         approver_emails:
           type: array
           maxItems: 3
-          nullable: true
+          nullable: false
           items:
             $ref: '#/components/schemas/email'
           example:
             - approver1@example.com
             - approver2@example.com
+            - null
           description: |
-            List of emails of employees that are approvers for this employee.
+            List of emails of employees that are approvers for this employee. Use null in case of no approver or to remove the approver.
         project_names:
           type: array
           nullable: true
@@ -1785,7 +1786,7 @@ components:
         delegatee_emails:
           type: array
           maxItems: 1
-          nullable: False
+          nullable: false
           items:
             $ref: '#/components/schemas/email'
           example: [ 'delegatee@example.com' ]
@@ -11368,7 +11369,7 @@ paths:
             application/json:
               schema:
                 type: object
-                additionalProperties: False
+                additionalProperties: false
                 properties:
                   data:
                     type: array
diff --git a/src/components/schemas/invitation.yaml b/src/components/schemas/invitation.yaml
index 37e0bb733..a16842cae 100644
--- a/src/components/schemas/invitation.yaml
+++ b/src/components/schemas/invitation.yaml
@@ -55,12 +55,12 @@ invitation_in:
     approver_emails:
       type: array
       maxItems: 3
-      nullable: True
+      nullable: False
       items:
         $ref: './fields.yaml#/email'
-      example: [ 'approver1@example.com', 'approver2@example.com' ]
+      example: [ 'approver1@example.com', 'approver2@example.com', null ]
       description: |
-        List of emails of employees that are approvers for this employee.
+        List of emails of employees that are approvers for this employee. Use null in case of no approver or to remove the approver.
 
     project_names:
       type: array