Is there a way to uninstall ChemDraw/ChemOffice components silently?

The Uninstalling switches to uninstall an installed product stored in the following registry location:

For 32 bit OS
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall]

For 64 bit OS
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall]

You need to open the various subfolders under the Uninstall folder, and check the display name (PerkinElmer...) that matches the following component that you are trying to remove from your machine:

For example, for v20.x, look for files like:
PerkinElmer ChemOffice 64-bit Support 20.0/20.1/20.1.1
PerkinElmer ChemOffice Suite 2020
PerkinElmer ChemScript 20.0/20.1/20.1.1