My wife has a car loan with her exhusband he refused to remove her name what makes it hard for us to get a mortgage or car loan for ourselves

Your wife's ex has no power to unilaterally remove her as an obligor on the car loan, as this would prejudice the lender (co-signers benefit the lender, giving it additional security for its loan).  Such a change would require the lender's consent, and it has no reason to consent.  Your wife's ex could theoretically repay the car loan, possibly taking out a new loan on his own for that purpose, but he may not have the ability to do that, even if he wanted to.  Moreover, absent a court order (such as a judgment of divorce) or an agreement which requires the ex to get the loan transferred to his name alone, I don't think he is obligated to do so.