To completely uninstall MotiveWave and remove all workspaces and historical data, first uninstall MotiveWave via Apps & Features in your Windows settings. Once this is complete you can now delete the following directories:
C:\Users\<username>\AppData\Roaming\MotiveWave\ - This is where your workspaces, historical data, and log files are stored.
C:\Users\<username>\MotiveWave Backup\ - This is where your automated workspace backups are stored.
C:\Users\<username>\MotiveWave Extensions\ - This is where custom studies and strategies are stored.