found it and I am on a shared host account. But the event was available in the Admin section.

AssemblyVersion: 5.6.2
PortalID: 0
PortalName: Sals Club
UserID: 3
UserName: supersal
ActiveTabID: 34
ActiveTabName: Superuser Accounts
RawURL: /Host/Superuser Accounts/tabid/34/portalid/0/language/en-US/Default.aspx
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer: https://salsclub.com/Host/Superuser%20Accounts/tabid/34/portalid/0/language/en-US/Default.aspx
UserAgent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 0718e823-176e-4a46-8209-7da6652738b8
InnerException: The DELETE statement conflicted with the REFERENCE constraint "FK_FolderPermissionUsers". The conflict occurred in database "salvig67", table "dbo.FolderPermission", column 'UserID'. The statement has been terminated.
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: System.Data.SqlClient.SqlConnection.
StackTrace:
Message: System.Data.SqlClient.SqlException: The DELETE statement conflicted with the REFERENCE constraint "FK_FolderPermissionUsers". The conflict occurred in database "salvig67", table "dbo.FolderPermission", column 'UserID'. The statement has been terminated. at System.Data.SqlClient.SqlConnection. (SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection. (SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe) at System.Data.SqlClient.SqlCommand.ExecuteNonQuery() at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteNonQuery(SqlConnection connection, CommandType commandType, String commandText, SqlParameter[] commandParameters) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteNonQuery(String connectionString, CommandType commandType, String commandText, SqlParameter[] commandParameters) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteNonQuery(String connectionString, String spName, Object[] parameterValues) at DotNetNuke.Security.Membership.Data.SqlDataProvider.RemoveUser(Int32 UserId, Int32 PortalId) at DotNetNuke.Security.Membership.AspNetMembershipProvider.RemoveUser(UserInfo user)