I am having the same problem. When I try to swipe to clear notifications there isn't the "clear all screen" to clear this notification. That is until I receive another notification then I scroll over and clear them and all are deleted BUT the voicemail notification still stays then you can't swipe past it again to get the clear all screen. I have called myself and left voicemail and it cleared then popped back up as notification (with no option to swipe past it again for the clear all screen). I went to the 3 phone apps and cleared the cache but didn't clear data because it said it would delete all files, settings and info so I was afraid to do this and lose all my contacts and info. PLEASE HELP!!! This is extremely annoying. This is the 3rd time in a year it has done this. Previously I "rebooted" my watch and phone then had to completely uninstall watch and reinstall it and god knows what else I did over several week period and it finally went away and is back again for good this time I'm afraid.
It will not erase your contacts.
I wish we could actually talk to Samsung about this, it's a glitch, if they still use that term.
By way of reassurance, this app can only access your contacts which are stored by one or more different apps. It cannot erase them. As far as erasing the data, that's only the data for voice mail.
You actually only really need to do this for one of two reasons.
1. You're like me and you like to keep the notification bar free for real notifications.
2. You need to know if someone has actually left you a voicemail.
Each and every time you get a voicemail and/or have completely turned off or restarted your phone you will need to go through the same process to get rid if the little notification thingy.
This was the only real solution provided. I couldn't figure out any of the other suggestions. Maybe those don't apply to S21 Ultra. '^^ Thanks for this application suggestion. It instantly removed the pesky notification! Samsung makes it nearly impossible to not use voicemail. Since I can't hear, it's nothing but bothersome. Constant reminders to do something I can't.