While updating the ubuntu 16.04 does not have a Release file Error [duplicate]

I updated my ubuntu 16.04 by sudo apt update and encountered this problem .

suraj@UTM-600001420:~$ sudo apt update
Hit:1 http://ppa.launchpad.net/gerardpuig/ppa/ubuntu xenial InRelease                              
Hit:2 http://in.archive.ubuntu.com/ubuntu xenial InRelease                                                                    
Ign:3 http://ppa.launchpad.net/linuxgndu/adt-raring/ubuntu xenial InRelease                                                   
Hit:4 http://in.archive.ubuntu.com/ubuntu xenial-updates InRelease                                 
Hit:5 http://ppa.launchpad.net/sunab/kdenlive-release/ubuntu xenial InRelease                 
Hit:6 http://in.archive.ubuntu.com/ubuntu xenial-backports InRelease
Hit:7 http://archive.canonical.com/ubuntu xenial InRelease                                     
Hit:8 http://in.archive.ubuntu.com/ubuntu xenial-security InRelease                            
Hit:9 http://ppa.launchpad.net/teejee2008/ppa/ubuntu xenial InRelease
Hit:10 http://ppa.launchpad.net/webupd8team/java/ubuntu xenial InRelease
Err:11 http://ppa.launchpad.net/linuxgndu/adt-raring/ubuntu xenial Release
  404  Not Found
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/linuxgndu/adt-raring/ubuntu xenial Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

How to fix this.?

Remove the erroneous repository with

sudo add-apt-repository -r ppa:linuxgndu/adt-raring

and update your sources:

sudo apt update