Delete disabled guest account

When I start up my computer I can choose between 2 users, namely myself, and a guest account which I try to delete since I am the only user.

The guest account shows as disabled, but I can not find a way to remove this, so that I can start up without entering a password.

Does anyone knows how too remove that account?

Think I am entered as administrator, but do not get the minus sign in black after opening the lock and clicking on that account.