Removing a repository from ‘apt directory’

These repositories are stored in '/etc/apt/sources.list.d/' in the form of '.list' files. Before removing any repository, we can list the contents of the directory by using the ls command:

sudo ls /etc/apt/sources.list.d/ -l
total 36
-rw-r--r-- 1 root root 69 Jul 10 2020 ansible-ubuntu-ansible-focal.list
-rw-r--r-- 1 root root 496 Mar 5 20:51 mysql.list
-rw-r--r-- 1 root root 132 Jul 10 2020 openjdk-r-ubuntu-ppa-artful.list
-rw-r--r-- 1 root root 132 Apr 25 2020 openjdk-r-ubuntu-ppa-artful.list.distUpgrade
-rw-r--r-- 1 root root 132 Jul 10 2020 openjdk-r-ubuntu-ppa-artful.list.save
-rw-r--r-- 1 root root 203 Mar 6 10:08 vscode.list
-rw-r--r-- 1 root root 138 Jul 10 2020 webupd8team-ubuntu-java-artful.list
-rw-r--r-- 1 root root 138 Apr 25 2020 webupd8team-ubuntu-java-artful.list.distUpgrade
-rw-r--r-- 1 root root 138 Jul 10 2020 webupd8team-ubuntu-java-artful.list.save

You can remove these repositories manually by removing the repository file.