This is a problem that occurs on specific versions of WildFly, see earlier postings such as - Always getting "Service jboss.data-source-config.<DS_NAME> is already registered" error when deploying vdb
The root issue is [WFLY-6773] Provide ability to start/stop Data Source creation without restart of server - JBoss Issue Tracker and it affects Teiid as outlined in [TEIID-4592] Creation, deletion and recreation of data source fails with exception - JBoss Issue Tracker
I had thought that later Designer versions helped mitigate the issue, but that may not be the case. Unfortunately WFLY-6773 wasn't addressed until WildFly 11. Teiid 10 does run on WildFly 11, but doesn't have a compatible Designer yet.
The simplest workaround should be to restart the WildFly server to let data source creating / deletion take full effect.