Here are the steps I would follow...
Upgrade the PSCs to 6.7, one at a time in the SSO
Use the converge tool to change the vCenters to embedded
Use the converge tool to decommission PSCs
You can upgrade to vSphere 6.7 update 3 and then do this. This is a simpler and uncomplicated method.
I remember that vSphere 6.5 Update 2 does not have such support. With the release of vSphere 6.5 Update 2d, it was announced that the Platform Services Controller (PSC) external type deployment will end.--
vBlogger, vExpert, Cisco Champions
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