Firstly, if you had your device linked to your Adobe account, you can try signing in to Adobe's website and accessing your account settings. Look for the "Devices" or "Authorized Apps" section, where you should see a list of devices connected to your account. Find the stolen device in the list and see if there's an option to remove it or deactivate the associated Adobe Scan app.
If you can't find such an option, the next best course of action would be to reach out to Adobe's customer support. They have dedicated channels to assist users in situations like yours. Explain the situation and provide any necessary details they might ask for, such as your Adobe account information and the serial number or IMEI of the stolen device. They should be able to help you remotely disable Adobe Scan or provide further guidance on what to do.
Remember, time is of the essence, so it's essential to act quickly to protect your personal data. I hope this information helps, and I wish you the best of luck in resolving this issue. If you have any further questions, feel free to ask. Stay safe!
If this does not help, you can sign out by clicking the profile icon-> then click the blue button saying "Forgot Password" to change the password, and that should remove any active sessions of your Adobe Account on other devices.