@pambee37
A Roku account is created/associated with an email account.
In order to create a "new" Roku account, you will need to use a different email address than you did originally.
Perform a Factory Reset on the Roku device and perform the setup/activation again with a new email address.
Alternatively, you could just change the password on your existing Roku account. Then delete/remove any Roku devices the ex has in his possession. You can do this from the online dashboard at https://www.roku.com/. (For good measure, change the password of the associated email address as well so ex cannot access that email).
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102