Fear is good for you. It stops you from taking un-necessary risks. From being reckless and un-thoughtful in what you do. Fear is natural.
It is a human emotion like all the others. Fear can be real and warranted - we fear punishment and retribution for our crimes, we fear threats from aggressive people, criminals etc ...
Or fear can be imagined and unwarranted - we fear the unknown, new places we have to visit, new situations in our lives, new people we have to meet, or we fear change from the comfort we're used to.
So fear, by itself, being natural, is not a sin. But how we react and deal with it can be. Too much unwarranted fear could be an insult to God in that we do not trust Him enough to look after us and care for us. Prayers are the answer.
Consider carefully what it is that causes your fear and if there is a genuine reason then seek help. Discuss the matter with a trusted relative or friend. If there is cause for concern then do not suffer and worry alone. Get help and let someone else see your problem from their perspective.
If however your anxiety is without foundation; and there is nothing practicable you can do to change the situation; trust in God. Tell Him how you feel and seek His help to calm you down. He has conquered fear. He has conquered the future. As well as evil. Forever.
Do not be afraid – I will save you. I have called you by name – you are mine. Isaiah 43:1