how can i hide category?

Question

You essentially want to add the following to $args:

'cat' => -65

One way to to this is to add the following line after $args = jr_filter_form();:

$args['cat']= -65;

Note the - will exclude that particular category ID from the results.

Reference: WordPress codex – query_posts() (see: “Exclude Categories From Your Home Page”)

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Additional Notes:

Admittedly, I’m not too familiar with the jr_filter_form(). It seems like you are using http://www.appthemes.com/themes/jobroller/ … they may already offer a built-in solution to customize the results, but I’m not a member so I can’t tell 🙂