If your number is still searchable on Truecaller after you opted out can be of different reasons:
1. If you are a Truecaller user you need to deactivate your account from the app.
2. It may take up to 24 hours before it’s removed due to caching processes.
3. The profile could be locally cached (saved) in your device so you need to empty your search results on that device and try again. Alternatively is to clear the cache memory of the device via the "phone settings > apps> Truecaller" on your Android device.