Deleted member continues to send spam.

I deleted a members account (actually I deleted 10 accounts which I believe are the same person) and they continue to send spam messages to other members from accounts on the site that have been deleted. How do they do that and is it possible for me to stop them?  Thanks

your cPaenl credentials are compromised.  You need to reset them. 

Do it as follows:

1.  Clean your computer that you have been logging into the cPanel/FTP with

2.  Change your passwords.  Do not go near your server until you have done this.

3.  Have your server scanned for viruses.

4.  See the other thread you commented in on this, I have listed tools to deal with spam.