I suggest to left the license expire automatically. I already returned licenses from your account, the license record is stored in local trusted storage in your PC.
If you like to remove local license - make backup of c:\ProgramData\FLEXnet\ (the folder is hidden by default) and delete content of that folder.
Sorry but for S32DS_ARM_v2018.R1 I still have the problem that it does not work (always the same error message appears). Is it because the license is already expired?