To edit or delete existing content, log in and then bring up the page you wish to edit. Look on the page for an "edit" tab. Depending on your user permissions, you will see this only for those pages that you submitted.
Clicking the edit tab will bring up a page with a form for changing the page. Here you can change the text and settings. Once you have the text and settings in a suitable form, click on the "Submit" button on the bottom of the form.
If you wish to delete the page (and you have appropriate permissions), click on the "delete" button near the bottom of the form. You'll get a second chance to confirm that you wish to delete the page, or to change your mind!
Note: Because meducator is very configurable, there may be additional ways of editing and managing content. For example under My Account -> Track you can see all your submitted content and edit it or delete it.