my girlfriends phone has had a os reload and a os upgrade to 7.1.342 and even deleted the twitter app and this is stuck on the multitask screen and have no idea how to get rid.
but as you can see in pic the icon is an unknow app.
Did you do a battery pull yet? If not, pull your battery, wait 30 seconds and put it back in.
Try and find it under options - device - application management
It should have the same icon and try to delete it from there (click the app and click the delete button).
If it doesn't work, your best bet is to reinstall the app, pull your battery, delete it and pull your battery. Should work.
OMG I had that before too... Um it went away after I deleted a screen capture app, I think its because the app had the option to send the screen capture to twitter, try deleting some and see if it goes away.