Make sure you have Administrator privileges on the machine.
Then proceed to the c:\User\<login-username>\ folder. For example, if you login name is "analyst", go to "C:\Users\analyst".
Once you are at this folder location, go to the View menu in Explorer and select Options/View. Find the option "Show hidden files, folders, and drives" and make sure it selected. Click "Apply to Folders", then "Apply" and "OK".
Then see if the folder AppData is present. Go into "AppData\Local\VirtualStore\Program Files (x86)".
For TerrSet, look for a TerrSet folder under "Program Files (x86)", and sub-folder under that called "License". If it exists, delete the "License" folder.
For IDRISI Selva, if the "IDRISI Selva\License" sub-folder exists, delete the subfolder "License".
If you are unsure of the above steps, please consult an IT person if possible.