List all the accounts this device had access to. This could be accounts for email, social media, messaging, dating, and banking, as well as accounts that may use this device for secondary authentication.
For any accounts your device had access to (such as email, social media or web account), you should remove the authorization for this device for them. This can be done by logging into your accounts and removing the device from permitted devices.
Once you have completed delinking your accounts, let's secure your passwords that may have been on the device.