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