10.6.3 Server – some users not showing in Workgroup Manager – how to delete with dscl so I can re-cr

I am running Mac OS X Server 10.6.3, and the last 4 users I created don't show in Workgroup Manager (or Server Preferences). They were there originally but now they are gone. They do show if I use dscl to list one of the groups they are members of. Also, these user accounts do not seem to be working. For example, trying to connect to a share point for which they should have access does not work with these account. Two questions: (1) Why would these 4 users be mysteriously not showing (or functioning)? (2) What's the syntax for using dscl to delete each of these users, so that I can then re-create them? Any help is appreciated. Thanks!