remove layout restriction for now

oit.layouts.yml

@@ -27,7 +27,7 @@ layout_left_sidebar_section:
     content:
       label: Content area
 layout_both_sidebar_section:
-  label: 'Both sidebar'
+  label: 'Both sidebars'
   path: layouts/both_sidebar_section
   template: layout--both-sidebar-section
   library: oit/both_sidebar_section

oit.module

@@ -813,6 +813,25 @@ function oit_menu_local_tasks_alter(&$data, $route_name) {
   }
 }
 
+/**
+ * Implements hook_layouts_alter().
+ */
+function oit_layout_alter(&$definitions) {
+    // an array of layouts to keep
+    $layoutsWhitelist = ['layout_onecol'];
+
+    // layouts that are required and cannot be removed
+    $requiredLayouts = ['layout_right_sidebar_section', 'layout_left_sidebar_section', 'layout_both_sidebar_section'];
+
+    $layouts = array_merge($requiredLayouts, $layoutsWhitelist);
+
+    $definitions = array_filter(
+        $definitions,
+        static fn(string $id) => in_array($id, $layouts, true),
+        ARRAY_FILTER_USE_KEY
+    );
+}
+
 /**
  * Implements hook_block_access().
  */