This is really a question that you should direct to Robinhood Customer Service or for that matter any other broker that you have an account with.
The answer in general can be found in the terms of service.
Section 8 - Important Information Needed to Open a New Account.
To help the government better detect the funding of terrorism and money laundering activities, federal
law requires all financial institutions to obtain, verify, and record information that identifies each person
who opens an account. Therefore, I understand that when I open My Account Robinhood will ask for My
name, address, date of birth and other identifying information. Robinhood may also ask copies of My
driver's license, passport or other identifying documents. I understand that Robinhood may take steps to
verify the accuracy of the information I provide to Robinhood in My Account application or otherwise, and
that Robinhood may restrict My access to My Account pending such verification. I will provide prompt
notification to Robinhood of any changes in the information including My name, address, e-mail address
and telephone number.
I further understand that if I attempt to access My Account from a jurisdiction subject to certain U.S.
sanctions or I am ordinarily resident in such a jurisdiction, or if you reasonably believe that I am
attempting such access or have become a resident in such a jurisdiction, you may restrict My Account,
and any pending orders may be cancelled. If this happens, I understand that I should contact
help@robinhood.com, and that I may be asked to provide supplemental information as part of this
process. I further understand that I must close My Account before establishing residency in any
jurisdiction subject to U.S. sanctions.
Basically this says that you must notify Robinhood that your address has changed promptly. Canada isn’t subject to US sanctions, so you’re fine on that front. Once you notify them that you are no longer a US resident, they will tell you if they want to continue to do business with you or not. If they will continue to do business with you, then you’re free to trade to your hearts content. If not, you may be able to transfer your account in kind to a Canadian or US Broker who will do business with you or to liquidate funds and have them write you a check.