In case you are using MultiCharts older than build 376.1220 you need to do a clean re-install because since build 376.1220 data cache has been added to MultiCharts. To make a complete clean uninstall:
1. Review MultiChart backing up article to make backup if needed.
2. Uninstall MultiCharts.
3. Make sure you have nothing in folders:
X:/Program Files/Common Files/TS Support/
X:/Program Files/TS Support/
Delete all the files/directories if any.

Note. X: is the drive MultiCharts been installed to (C: by default).