Disable UI in chrome://settings/internet and details popup for policy-managed networks.

chrome/browser/resources/options/chromeos/internet_options_page.css

 #inetTitle {
   border: none;
 }
 
 #network-general-div {
   -webkit-margin-start: 15px;
 }
 
 #networking-controls {
   display: -webkit-box;
 }
 
 .networks {
   -webkit-margin-start: 15px;
   padding: 2px;
 }
 
 .network-password {
   left: 0px;
   position: relative;
 }
 
 .network-password > input, .network-password > select {
   width: 200px;
 }
 
 .network-item {
   -webkit-box-align: center;
-  -webkit-padding-start: 30px;
+  -webkit-padding-start: 10px;
   border: 1px solid rgba(255,255,255,0); /* transparent white */
   border-radius: 2px;
   display: -webkit-box;
   height: 35px;
 }
 
 .network-item:not([connecting]):hover {
   border-color: hsl(214, 91%, 85%);
   background-color: hsl(214, 91%, 97%);
 }
 
 .network-item[connected] {
   background-image: -webkit-linear-gradient(rgba(255, 255, 255, 0.8),
                                             rgba(255, 255, 255, 0));
   background-color: hsl(214,91%,89%);
   border-color: hsl(214, 91%, 65%);
 }
 
 .network-item[connected]:hover {
   background-color: hsl(214, 91%, 87%);
   border-color: hsl(214, 91%, 65%);
 }
 
 .network-item[connecting] {
   background-color: hsl(214, 91%, 97%);
   border-color: hsl(214, 91%, 85%);
 }
 
+.network-item > .controlled-setting-indicator {
+  -webkit-margin-end: 5px;
+  width: 16px;
+}
+
+.hide-indicators .network-item > .controlled-setting-indicator {
+  display: none;
+}
+
 .network-item-text {
   -webkit-padding-start: 30px;
   background: left center no-repeat;
   cursor: default;
   display: table-cell;
   height: 32px;
   line-height: 100%;
   max-width: 320px;
   overflow: hidden;
   vertical-align: middle;
@@ skipping 92 matching lines @@
 }
 
 #ipConfigList .name {
   width: 40%;
 }
 
 #ipConfigList .value {
   -webkit-box-flex: 1;
   color: #666;
 }