I have the following query and get the below error message:
update `wp_posts` set `post_excerpt` = replace( `post_excerpt`, \"[av_font_icon icon=\'ue82d\' font=
You should escape the single quotes in the string you are matching, using ''
Why don't you use the "Database Search And Replace Script In PHP"? All you have to do is place it in the root folder and run it in your browser. https://interconnectit.com/products/search-and-replace-for-wordpress-databases/
That's what I use and have never had a problem. Just make sure to make a back up just in case.
Run a search for the short code and replace it with an empty field.