This is a bit broad of a question since I don't know to which type of links you are referring -- links to external URLs? links to course Files or Google docs? links to other parts of your course?
Is the link in a textbox? Or is it a link placed directly in a Module.
If it's in a textbox, first you'll want to select the text with the link and remove the link. Then create a new link with the correct information.
These guides may help: