Both of these commands, msiexec /uninstall CylancePROTECT_x64.msi UNINSTALLKEY="------" and msiexec /x CylancePROTECT_x64.msi UNINSTALLKEY="-----", are failing with this error:
Cylance was pushed out to these windows endpoints through Native Apps and the above commands were added to the uninstall command.
For uninstalls I always use /x and the GUID instead of the MSI name. The MSI name requires you to know where the file is whereas the GUID does not.
My suggestion is to install it on a device, find it in the registry (HKLM\SOFWATE\Microsoft\Windows\CurrentVersion\Uninstall and its WOW6432NODE equivalent) and look at the uninstall string there. That should tell you the GUID to use. If it doesn't, then you can use an application like Orca or InstEd to read the MSI and find the code in there. That should then work.
missing error message
For uninstalls I always use /x and the GUID instead of the MSI name. The MSI name requires you to know where the file is whereas the GUID does not.
My suggestion is to install it on a device, find it in the registry (HKLM\SOFWATE\Microsoft\Windows\CurrentVersion\Uninstall and its WOW6432NODE equivalent) and look at the uninstall string there. That should tell you the GUID to use. If it doesn't, then you can use an application like Orca or InstEd to read the MSI and find the code in there. That should then work.