UnInstalling Sage 300 Work station

Our client is running Sage 300 Advanced Version 2016. We had previously installed the software in an old server and when the client purchased a new server we transferred the software to it and thus we had to uninstall all workstations and install the software afresh in the workstations pointing it to the new server. Two workstations have completely refused to uninstall thus one is not able to install the workstation pointing it to the new server.

Is there a way of deleting the sage installation from the two workstations from the program files? once I delete the program files is there any other thing I need to do to the Registry files?

All responses will be highly appreciated.