Can I delete SQL Server 2008 R2 "audittrace" (.trc) files
Are those files really from C2 audit?


The audit file format is audittraceyyyymmddHHMMSS.trc

After you disable C2 audit using 

EXEC sp_configure 'c2 audit mode', 0
go
reconfigure with override


and you are absolutely sure that you dont need the audit files, you can delete the files.


  If so, can I safely remove them without worring about data stored in databases?


The C2 Audit Mode uses SQL Trace to capture audit events, which are stored in trace files i.e. they are not stored in database, unless you have a job that loads the files into a database.

Note : The C2 security standard has been superseded by Common Criteria Certification.