Canada Fidelity account vs US Fidelity account

Hello

I started working for my company at their Canadian branch and was given company stocks there over time the longer I worked. I then moved to their US branch and they opened a whole new Fidelity account for me to give company stocks. What is the best way to cut tax ties with Canadian Fidelity? Should I sell all my stocks and buy them again on my US account? Is there a way to absorb the Canadian account into my US in Fidelity? I have not sold any stocks yet but my Canadian stocks are still vesting over time.