Those cultural changes are going to take time. Look how long things took for minorities in the US. Eliminating Santa Anna reduces the political chaos and inept generalship that plagued Mexico.
It's still probably not enough. Mexico suffered from a lot of treacherous, reactionary, oppressive, self-serving men. Santa Anna was merely one of the worst.
He was not the worst

Getting rid of him is not needed

All you need is for him to not get corrupted like his latter reign. He was an OK general not inept, just unlucky an facing many revolts and facing an enemy much stronger tha him. Let me guess you believe all that propoganda bull that his enemies smeared about him

Half of what they said isnt true, he is as egoistic as Polk. Political chaos was not due to him, he actually
united the mexicans, Mexico had inept generals killing santa anna will not change that. The POTUS before Anna during the pastry war screwed mexico over, and before Anna civl war and political rivalry completly plagued mexico. By getting rid of Anna said political parties remain. Last I checked that is a bad thing. He acted as the unifing force in mexico. True he was a corrupt son of a bitch but that was during his latter life. In fact he was a good general cause he crushed most of the rebbelions in northern mexico, united mexico, defeated General Urea who tried revolting and he duped Polk. So he was in no way inept, getting rid of him does not solve mexicos problems, it just makes them worse. In fact their are basically very valid PODs that work. One is mine, another is an earlier union in mexico, Anna inherited a country wth a shitload of problems. SO sadly your point is incorrect. Please do a little more research on Santa Anna.