Can a person legally tow the vehicle away from another person without consent?

My friend wants to re-possess a vehicle that someone else currently has in their custody. My friend (A) has his name on the title until his friend (B) pays him the full amount. Person B has made payments already but has defaulted on them. Person A wants to take it back from Person B even though there is a verbal contract stating it could be used and owned by Person B until he pays it all (no payment due date has been discussed).