Someone used my phone now in the top left hand corner is a blue and white phone symbol and my supplementary settings has been deleted. I can't get rid of the blue and white phone out of the corner. What do I do
Welcome to Android Central! Was this someone you know, or are you saying the phone was lost and then recovered? Do you know if this someone swapped SIM cards temporarily to use the phone on their own carrier?
If you don't know this person, or if you don't trust them, probably the best thing to do is to do a factory reset, then set the phone back up as if it were brand new. Make sure to back up or save any important data on the phone before you do the reset.
If the blue and white icon in question is on the left side of the notification bar, you can swipe that down and see what notification it pertains to. That will likely answer a lot of your questions.
And what do you mean by "supplementary settings?" That's not standard nomenclature and there are settings all throughout the phone and apps, so I have no idea what you are referring to. You also can't delete a setting, so are we to assume you mean reverted to their defaults?