Depends on what you mean with "clear". You cannot remove individual
licenses from the Licensing manager.
You can however completely deactivate and then uninstall the TS
Licensing Service and then by hand remove all remaining files,
including the database.
If you afterwards want to reinstall the LS again and install the same
License Packs, I think you have to phone the Clearinghouse, explain
the situation and ask them to re-issue your licenses.