How can i use betamethasone dipropionate cream to make my foreskin to be shorter?

Do you mean looser?: Cream is uised to loosen foreskin iF & when foreskin is too tight to retract easily, i.e corrects phimosis. It does not make foreskin shorter. Pull back foreskin as far as omfortable, then apply to narrow constricted area of skin twice daily until skin is nice & loose. Always return foreskin over glans when you finish, once foreskin retracts all the way. See urologist if unsucessful.