You ask for some way of completely eradicating irritability. The inclination to irritability is given us to use against sin, and we were never meant to use it against our fellow men. When we do, we act contrary to our true nature.
But let thine apparel be plain, not for adornment, but for necessary conversing: not to minister to thy vanity, but to keep thee warm in winter, and to hide the unseemliness of the body: lest under the pretence of hiding the unseemliness, thou fall under another kind of unseemliness by thy extravagant dress.
We ought not to grieve or become irritated at anything because, by frequent vexation and irritability, we form the morally and physically very injurious habit of irritability, whilst by bearing opposition with equanimity we form the good and useful habit of enduring everything calmly and patiently.