dynamically remove submitHandler from jQuery Validate to allow normal PayPal 'donate' button action

I have to add a PayPal donate button to the middle of an angular donation form, so nesting the paypal generated form tags within the donation form tags. The donation form is processed by an old version (1.12) of jQuery Validate, so no access to the .rules() functions. I found a way past the validation requirements with this answer (commented out code below), but the problem is the submitHandler takes an argument of 'form' which is always the parent form element (the full donation form). Ideally, I'd like to disable jQuery validate all together once paypal is selected. Here is the function I call when the user chooses 'credit card' vs 'paypal' and it is correctly going into the else when paypal is selected.

    $scope.payByCreditCard= function(cc_true) {
    if(cc_true){
        $scope.creditCardDetails = true;
        $scope.submit_text = "Submit Donation";
        $scope.method_type = "donate";
    } else {
        $scope.creditCardDetails = false;
        $scope.submit_text = "Continue Donation on Paypal";
        $scope.method_type = "startDonation";
        // var settings = $('#donationForm').validate().settings;
        // delete settings.rules;
        // $("*").removeClass("required");

    }
};

and the jQuery Validate calls with submit handler:

$('#donationForm').validate({
    rules: {
        otherDonationAmount: {
            money: true,
            required : true
        }
    },
    errorPlacement : function(error, element) {
        if (element.attr('id') == 'donationAmount') {
            error.insertAfter(element.parent());
        } else {
            error.insertAfter(element);
        }
    },

    submitHandler: function(form) {
        $('#donation-errors').remove();
        window.scrollTo(0, 0);
        $("#donationForm").hide();
        $("#donationForm").before('<div class="well donation-loading" style="text-align:center;">' +
                         This may take a few seconds. Do not leave the page or click the back button.' + '</div>');

    }
});

What's happening is I disable the validation, but then when I click the paypal donate button, the submitHandler function is triggered and it tries to process the whole donation form, rather than following what's in the paypal generated code:

                            <form action="https://www.paypal.com/xxx/xxx" method="post" target="_top">
                            <input type="hidden" name="" value="">
                            <input type="hidden" name="" value="">
                            <input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_donate_LG.gif" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!">
                            <img alt="" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1">
                        </form>

So, I'm looking for a way to disable jQuery validate as both a validator and submitHandler if a condition is met (The user selects PayPal). I hope this makes sense and thanks in advance.