Hi, We have a requirement to enable the browsers native spell check in RTE. I found this article Troubleshooting RTE and have managed to turn on the browsers spell checker, but I have not had much luck on disabling the Context Menu. I have tried some variations of this CKEditor config:  

CKEDITOR.editorConfig = function (config) {
  config.removePlugins = 'elementspath,contextmenu,liststyle,tabletools,tableselection';
  config.disableNativeSpellChecker = false;
}

Here's a snippet from the article:

Browser spell checking

By default, browser spell check functionality is disabled in Pega applications. If you want to enable native browser spell checking, complete the following steps:

1. In UserWorkForm, set the window.disableNativeSpellChecker option to false to enable it.
2. If the Context Menu plugin is enabled, users must select and hold the Ctrl key when right-clicking misspelled words to see the suggested corrections.