add static messages to admin confirmation messages

src/registrar/admin.py

@@ -1326,6 +1326,7 @@ class UserPortfolioPermissionAdmin(ListHeaderAdmin):
     search_help_text = "Search by first name, last name, email, or portfolio."
 
     change_form_template = "django/admin/user_portfolio_permission_change_form.html"
+    delete_confirmation_template = "django/admin/user_portfolio_permission_delete_confirmation.html"
 
     def get_roles(self, obj):
         readable_roles = obj.get_readable_roles()
@@ -1631,6 +1632,7 @@ class PortfolioInvitationAdmin(BaseInvitationAdmin):
     autocomplete_fields = ["portfolio"]
 
     change_form_template = "django/admin/portfolio_invitation_change_form.html"
+    delete_confirmation_template = "django/admin/portfolio_invitation_delete_confirmation.html"
 
     # Select portfolio invitations to change -> Portfolio invitations
     def changelist_view(self, request, extra_context=None):

src/registrar/templates/django/admin/portfolio_invitation_delete_confirmation.html

@@ -0,0 +1,17 @@
+{% extends "admin/delete_confirmation.html" %}
+
+{% block content_subtitle %}
+    <div class="usa-alert usa-alert--info usa-alert--slim">
+        <div class="usa-alert__body margin-left-1 maxw-none">
+            <p class="usa-alert__text maxw-none">
+                If you cancel the portfolio invitation here, it won't trigger any emails. It also won't remove the user's
+                portfolio access if they already logged in. Go to the 
+                <a href="{% url 'admin:registrar_userportfoliopermission_changelist' %}">
+                    User Portfolio Permissions
+                </a>
+                table if you want to remove the user from a portfolio.
+            </p>
+        </div>
+    </div>
+    {{ block.super }}
+{% endblock %}

src/registrar/templates/django/admin/user_portfolio_permission_delete_confirmation.html

@@ -0,0 +1,12 @@
+{% extends "admin/delete_confirmation.html" %}
+
+{% block content_subtitle %}
+    <div class="usa-alert usa-alert--info usa-alert--slim">
+        <div class="usa-alert__body margin-left-1 maxw-none">
+            <p class="usa-alert__text maxw-none">
+                If you remove someone from a portfolio here, it will not send any emails when you click "Save".
+            </p>
+        </div>
+    </div>
+    {{ block.super }}
+{% endblock %}

src/registrar/tests/test_admin.py

@@ -1549,6 +1549,24 @@ class TestPortfolioInvitationAdmin(TestCase):
             request, "Could not send email notification to existing organization admins."
         )
 
+    @less_console_noise_decorator
+    def test_delete_confirmation_page_contains_static_message(self):
+        """Ensure the custom message appears in the delete confirmation page."""
+        self.client.force_login(self.superuser)
+        # Create a test portfolio invitation
+        self.invitation = PortfolioInvitation.objects.create(
+            email="testuser@example.com",
+            portfolio=self.portfolio,
+            roles=["organization_member"]
+        )
+        delete_url = reverse(
+            "admin:registrar_portfolioinvitation_delete", args=[self.invitation.pk]
+        )
+        response = self.client.get(delete_url)
+
+        # Check if the response contains the expected static message
+        expected_message = "If you cancel the portfolio invitation here"
+        self.assertIn(expected_message, response.content.decode("utf-8"))
 
 class TestHostAdmin(TestCase):
     """Tests for the HostAdmin class as super user