Something like this should work:
$('a').filter( function() {
return ~$(this).text().toLowerCase().indexOf('fixed');
} ).closest('tr').find(':checkbox').hide();
The .toLowerCase() makes it case-insensitive, and the ~ is there because if indexOf() doesn't match the string, it returns -1 (0 means "at position 0"), so the bitwise NOT converts -1 into the falsey value of 0, and everything else into truthy values.
You can improve this by adding a selector to the front so it doesn't crawl every single <a> tag - something like $('table').find('a') or better yet the ID, or something more identifiable.
.css( {"display": "none" })