The log file locations can be changed using the following steps. The CompleteFTP manager should still be able to view the log files, after changing the location.
1. Open CompleteFTPService.exe.config, which is in the install directory. This may require administrative privileges. This is basically a log4net configuration file, and you can change the location of log files there.
2. Make a copy before modifying it!
3. Modify
%folder{{ '{' }}CommonApplicationData{{ '}' }}\\Enterprise Distributed Technologies\\Complete FTP\\logs\\Diagnostics.log
using similar paths to set your desired location, e.g.
D:\\CompleteFTP\\logs\\Diagnostics.log
4. Restart the CompleteFTP service, in order to re-read the configuration file.
CompleteFTP should now be logging to your new log file location.