uninstall - apt-get giving warnings on programs I've uninstalled

I uninstalled a program using the command

sudo apt-get --purge remove programName

but when I ran sudo apt-get update it still return errors on that program's keys. So I then uninstalled the program's key using

sudo apt-key del AAAAAAAA

but then I get errors from sudo apt-get update about the keys. Specifically I am trying to completely remove Epson drivers, and these are the errors:

W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://download.ebz.epson.net/dsc/op/stable/debian lsb3.2 Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E5E86C008AA65D56
W: Failed to fetch http://download.ebz.epson.net/dsc/op/stable/debian/dists/lsb3.2/Release.gpg The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E5E86C008AA65D56
W: Some index files failed to download. They have been ignored, or old ones used instead.

I just want everything about these Epson drivers removed so I don't get bothered about it every time I run update.