To uninstall Mastercam 2018, you'll need to delete, or rename some files before uninstalling the program.
First go to the C Drive\Users\Public\Public Documents, and find the Shared Mcam folderfor the version you want to uninstall. Either delete this folder, or rename it if you want to save the files.
Go back to the Users, and this time go into your log in on the computer, C:\Users\your user name\ documents, and look for the "My Mcam" folder, and delete or rename it.
Go back to the C drive, and go into Program Files. C:\Program Files, and delete the Mcam folder there.
Now you need to delete the Mastercam Window's Registries, do this by pressing the Windows Key on the key board and "R", and then when the "Run" command comes up, type "regedit" to get the registry editor to come up.
Once in the Registry Editor, go to "HKey_Current_User", expand it, and go down to "Software", then to "CNC Software, Inc", and delete the registry for the correct version.
Collapse the "HKey_Current_User", and expand the "HKey_Local_Machine". Then go down to "Software", then to "CNC Software, Inc", and delete the registry for the correct version there too.
Once you're done deleting the registries, you can uninstall Mastercam.
Right click on the "Start Menu", and go to "Programs and Features", then right click on the version of Mastercam you're uninstalling, and select "Uninstall"