If God created free will, then you bet He has free will.

By definition, evil is something somebody decided to be not good. What is good and what is evil is different for every person. When people live in groups, they either have to vote on what all of them consider good and evil, or allow some of them to decide for everyone else. The more people you have, the more difficult it is for everybody to agree on what is evil. That is why laws of countries change all the time. 

 

If our universe is to survive, there has to be one person who ultimately decides what is right and what is wrong. Without that, the universe will go into ruin. We see the results of what happens when different persons disagree on what is wrong when we see wars, conflicts, and crimes that happen on Earth. We need somebody who is above us to decide what is right and what is wrong. We need a God, only One God. 

 

This God would be deciding what is evil. He would set the rules. Before He created the rules, there were no rules, and there was nobody else besides Him to decide whether those rules are good. So by definition, God cannot do evil, because there is nobody above Him to judge His opinions.

 

For anybody below this God, we better hope these rules are good. Fortunately, with all the good around us and all the free good gifts we were given, we can see that this God who created everything is good. Also fortunate for us is that this God never changes. What He decided to be good will always be good. Imagine if gravity would one day work one way and another day work differently? If one day you wake up and gravity no longer pulls you towards the Earth, but pushes you away from the Earth? There would be terrible chaos. Same thing with anything in nature. 

 

When we look at the laws of nature, we can see that century after century they remain the same. That shows us that whoever created these laws does not change. So no, God cannot start doing something that He decided to be evil before. And that is a very good thing.