To maintain the CA Dataquery User Table (DQU), there is a utility called DQUSERMT. This is explained in the Core documentation, in the Administration section.
One important thing to note here is that the input to this utility is column-specific.
Here is an example input showing different commands - there are more explanations in the documentation.
//SYSIN DD *
SIGN/ON DATACOM-INSTALL PASSWORD NEWUSER
ADD USER=DJ-TEST1,SUBMIT=Y,EXPORT=Y,SQLDQL=Y,SQLDDEF=Y, X
ADD USER=DJTEST2 COPYFROM=TESTUSE1