Hello,
Clipboard History is a part of Parallels Toolbox. It allows you to save the history of data in Clipboard. But Clipboard History doesn't encrypt data.
/private/var/folders/ - it is temporary directory that should be cleaned by macOS after restart.
If you don't want to use Clipboard History tool you can clean all data that was saved and turn the tool off:
1) Open Clipboard History tool, right click on any item and choose 'Delete All'.
2) Open preferences of Clipboard History (cogwheel in right top corner) and turn OFF the option "Open when Mac starts".
3) Quit from the tool.
After this the tool will stop collecting your Clipboard Data and will not be started on macOS startup.
Last edited: Sep 16, 2019