if have a function that opens up a modal

return {
    'type': 'ir.actions.act_window',
    'name': 'OI/TI Visit',
    'res_model': 'ec.medical.oi.ti.platform.attempt',
    'res_id': oi_ti_platform_attempt.id,
    'view_mode': 'form',
    'view_id': self.env.ref('ecare_medical_history.view_ec_medical_oi_ti_platform_attempt_form').id,
    "target": "new",
}

i want to disable the "x" (close) button on this popup modal i tried making a custom header but it doesnt overwrite the default header i tried js 

$(function(){
$(".modal-header button").hide();
});

it removes it but it messes with the behaviour of the modal when i try to open it from a different function too is there a way to pass context and then access it in js so i can add an if statement? if so how or if theres any other method