How do I get rid of the red bubble on my phone option?

I have a red bubble on the phone selector I have checked all my missed calls and it isn't that! At the end is the voicemail box and it is above that but it will not go! Been trough all the voicemail settings and nothing is happening if you could help me it would be a huge help because it annoys me so much the act that it has been their for around 2 weeks :(