I'd advice to start by installing the AceEditor module (using Module Manager in the extensions menu). After that go to user preferences and select AceEditor as your syntax highlighter.
Now, go to the news module, go to the summary templates tab and open the sample template.
Look up the part of the code that displays the summary and just delete it.
it starts with this: {if $entry->summary}
News Module Help
Re: News Module Help
You need to make a custom summary template that calls only the parts you want then in sidebar News tag call that template summarytemplate='name of template' ...