Part of macOS
kernelmanagerdSystem extensions
○ Leave it
Loads drivers and system extensions.
What it is
Manages kernel and system extensions that apps and hardware install.
If you stop it
macOS starts it again straight away. Leave it.
The verdict
○ Leave it. Part of macOS, or something that starts again by itself. You never need to close these.
In Activity Monitor
kernelmanagerdkernelmanager_helpercorekdldlogkextloadsdsysextd
From Procession’s guide, in the words the app shows.