Formidable errors in functions file after removal

I installed Formidable forms to test and chose to go with Gravity Forms instead. Now when testing sign up, I get a warning message with a call to fomidable in my functions.php file. I tried to install and remove formidable again to see if that would fix it but I still get the error message.

Warning: fopen(/home/wpinsta/public_html/wp-content/plugins/formidable/formidable.php) [function.fopen]: failed to open stream: No such file or directory in /home/wpinsta/public_html/wp-includes/functions.php on line 3508

Warning: fread(): supplied argument is not a valid stream resource in /home/wpinsta/public_html/wp-includes/functions.php on line 3511

Warning: fclose(): supplied argument is not a valid stream resource in /home/wpinsta/public_html/wp-includes/functions.php on line 3514

Thanks for your help.