Are you frustrated with the voicemail icon constantly appearing in your Android notification bar? You can clear the app's data on your phone to remove the notification, but this is just a temporary fix. If this problem happens frequently, consider contacting your network provider or performing a factory reset on your phone.
Steps
Clear app data on your phone

Open the Settings app on your device. If the voicemail notification keeps showing up and you're certain you don't have any voicemails in your account, resetting the app's data is a temporary solution to fix the issue.

Tap on "Apps" (Applications) or "Application Manager" (Application Management). The list of apps on your phone will appear, usually defaulting to the "Downloaded" (Downloaded) tab.

Swipe to the "All" (All) section. All installed apps on the device, including system apps, will be shown.

Scroll down to find "Phone" (Calls). Typically, there are many similar applications available.

Tap on the first "Phone" app in the list. The app's settings will open up.

Tap "Clear Data" (Clear Data) and confirm. The app's data will be deleted, but this will not affect your contacts.

Repeat the process for the remaining "Phone" apps. Ensure that you perform the data clearing step for each "Phone" or "Phone/Messaging Storage" app (Calls/SMS Storage).
Scroll down and tap on the "Voice Mail" app (Voicemail) to access its settings.

Tap "Clear Data" and confirm. Once the data is cleared, the notification will disappear.

Disable and re-enable notifications. In the Voice Mail settings, uncheck "Show notifications" and confirm that you wish to disable it. After turning off the option, check the box again to turn notifications back on. Your voicemail notifications will be refreshed.

Repeat this method when restarting the phone. There's a chance the notification will appear again when you reboot your device. Clear the app's data to remove the notification, or try the long-term fix outlined below.
Long-term solution

Check your messages again. Even if you've checked and found no new messages, call your voicemail once more. It's possible an old message was missed and is causing the notification. You must ensure there are no unreviewed messages in your voicemail inbox.

Contact your carrier's support center. Sometimes, a notification persists because of a voicemail issue that needs to be reset by the carrier. Explain to them that the voicemail icon is stuck in the notification bar and ask them to reset your voicemail inbox. This solution is quite effective for many users.

Factory reset your Android device. This is a last resort option, but it may resolve your issue. Be sure to back up your data before proceeding, as everything will be wiped clean.
- You can quickly back up data by connecting your phone to a computer and copying all important files. Ensure that your image and music library is saved before performing the reset.
- Sync your device with your Google account to back up your contacts. After resetting and logging into your Google account, your contact list will be restored.
- You can perform the reset by navigating to the "Backup & reset" section in the Settings app. Tap on "Factory data reset" in the menu to begin.
