Click the Profiles tab>Manage Seller Details, choose the one you want to edit and click the edit button. Wait for the text to load, then click "Switch to: Standard". It'll give you the WYSIWYG editor.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .