When a GRANT LOGON statement is processed for one or more user names, a logon control record is created for each user_name/host_ID pair specified. Any existing control record for a particular user_name/host_ID pair is replaced. The logon control record created for a particular user name persists until that user is dropped.
See also the information for DROP USER in Teradata Vantage™ - SQL Data Definition Language Syntax and Examples, B035-1144.