How can I delete that it is " connected as a media device?

[AC Question]

Since then my battery is draining.

 

[BioFanatic]

Is your phone plugged into anything? That's what that icon means.

If it's not plugged into anything, I'm guessing it was recently. Sometimes that notification is finicky and doesn't clear. I find plugging it in then removing the plug often clears that.

Your battery drain is probably normal, just from you turning on the screen to check this, or from normal phone use.