资料来源：http://askubuntu.com/questions/107177/how-can-i-remove-gpg-key-that-i-added-using-apt-key-add

大部分软件手工增加官方软件源方法：参考（https://help.getsync.com/hc/en-us/articles/206178924-Installing-Sync-package-on-Linux 和 https://www.linuxbabe.com/desktop-linux/install-bittorrent-sync-ubuntu-16-04-official-deb-repository）

sudo nano /etc/apt/sources.list

Append the following APT line at the end of this file.

deb http://linux-packages.resilio.com/resilio-sync/deb resilio-sync non-free

Save and close this file.

In order for APT to authenticate packages from the above repository, we need to import BitTorrent Sync’s public key. First download the public key with wget.

wget https://linux-packages.resilio.com/resilio-sync/key.asc

Import the key with apt-key.

sudo apt-key add key.asc

Now let’s update local package index and install BitTorrent Sync

sudo apt updatesudo apt install resilio-sync

Managing BitTorrent Sync

To start BitTorrent Sync, use systemctl

sudo systemctl start resilio-sync

Enable BitTorrent Sync to auto start when Ubuntu 16.04 is booted up.

sudo systemctl enable resilio-sync

Check its status.

systemctl status resilio-sync

如何删除呢？

First you need to find the key id of the key you added. Do this by the command:

sudo apt-key list

It will list all the keys that you have, with each entry looking like this:

pub   1024R/B455BEF0 2010-07-29uid                  Launchpad clicompanion-nightlies

Once you have figured out which key to remove, use the command sudo apt-key del <keyid>where is replaced with the actual keyid of the key you want to remove from your keyring.

nits@nits-excalibur:~$ sudo apt-key del B455BEF0[sudo] password for nits: OKnits@nits-excalibur:~$ apt-key list | grep clicompannits@nits-excalibur:~$