Hi,
I hope you got the answer. Just in case you didnt, Linux based operating systems support open-vm-tools to avoid installing vmware tools separately.
if your VM shows "guest managed" it means that the VM is using open VM tools which came with the operating system.
Nothing to worry about it, it was meant to help the admins
Refer the following link for more details
Using Open Virtual Machine Tools
Regards,
Ameen Munaf