I already pretty much deleted them. I had a phone from 1986, with an old fashioned tape answering machine, and a few of those cockroaches were put in. Then they went out of date, and I changed them. Then, in 1996, I got tired of all the problems the tape machine was giving me (especially how easy it was to reset and lose the messages), so I got another phone. This time, I didn't even bother to put any of the witlesses in it.
Instead, I have my phone book. However, I do not use it to dial any of the witlesses. Rather, I would see if they are still at the same addresses or (I wish) they would be forced to move to another territory or start seeing them not listed.