There is not a way to fix this once you have deleted the user.
If you delete a spammer they can just signup again and spam again. You should be suspending the sapmmer instead which blocks them from signingup again using the same username or email address.
If you are using the latest 10.15 version then the built in spam cleaner tool can delete all posts (if they have made less than 50 posts) and PM's made by a spammer, suspended their account, and block their IP all from one page.
The latest version also connects to StopForumSpam to block known spammers from signing up to your forum.
Forums using the spam tools in the latest version have reported drops of over 90% in spam within their forums.