In order to Edit a Content Builder e-Folder:

Go to Content Builder

Click on Our e-Folder(s)

Hover over the e-Folder you wish to edit

Click on Edit to edit the e-Folder content

The following pop-up will appear. Click Yes to continue, No to close the pop-up

Make any changes and click Next

Click Next on all following steps if you do not wish to make further changes

Click Next

Click on Publish on the final step to save changes