want to change custody of my child, i am his mom.

I am mom and have custody of my son. My son visits his father on weekends and stays with him. I want to sattle in another country and want to give custody back to his father. He agreed for share custody and allowed me to see my son on Skype and can take him on weekends whenever I come to Canada. I will have access to my child whenever I need. We both have no criminal record and we don't drink. There is no harm for my son living with his father.