querystring error

I have a page whitch I load with different querystring variables. Sometimes (not every time!) i get a warning like this:

Warning: Undefined variable: delete in
/home/q/quickmes/www/alfa/history.phtml on line 42

this happens when i do not use the variable (in this case "delete").
This does not look good on my page...
what should i do to get rid of the warning?

You can lower the error reporting level in php.ini

Hi,
Well I don't have access to the php.ini file (I've got my homepage at a webhotel).

Is there any other way ?..

You can set error reporting within a script using the error_reporting() function. It uses a bit mask for determining the types of errors/warnings returned. You want to turn off e_notice(mask 8). The remaining values are e_error(mask 1), e_warning(2), e_parse(4), e_core_error(16) and e_core_warning(32).

So you should use:

error_reporting(55);

That should do the trick.