Scroll down to the Certifications card on the right.
Hover over the Certification you'd like to edit, then click the Edit (pen) button.
When you are done editing, don't forget to Save!
To cancel any changes you've made, simply click the left arrow in the top bar. You will be prompted "You have unsaved changes. Are you sure you want to leave without saving?" Just click 'OK' and your changes will not save.