The only time Netmaster requires Datacom is if you are running ReportCenter over Datacom/AD.
To check this, go to SDSF and browse the LOG01 output for your Netmaster region.
If you are running ReportCenter, you will see this during startup
N11414 SYSTEM CONFIGURED WITH REPORTER FEATURE - R7.6 LEVEL 1212
You can also check your RUNSYSIN for PPREF='PROD=REPORTER'.
If that feature is not defined, Netmaster is not utilizing Datacom and there is no impact if Datacom is removed.