Once you have added a link to a page, announcement, assignment, etc. in your Canvas module you can edit this link using the Link Options menu in the Rich Content Editor (RCE).
When in Edit mode on your page, highlight the text in your content which contains the link.
Click the Link Options link that appears underneath when this text is selected. Alternatively, can click the Link Options arrow in the RCE menu and select the Edit Link option.
In the Link Options menu, you can edit the hyperlinked text in the Text field. You can edit the URL in the Link field.
To save your changes, click the Done button.
To remove a link, click the Link Options arrow and select the Remove Link option.
Click the Save button to save the changes in your page/discussion, etc.