I worked with VMware support to upgrade the vROPs nodes config from Medium to Large.
Also, the support person directed me to the same VMware KB article Removing a node from a VMware vRealize Operations Manager 6.x cluster (2107711) | VMware KB
He asked me to take snapshot of all vROPs nodes and said that there will be no data loss, as we also upgraded the disk size of vROPs nodes to accommodate for data .
But, eventually we dropped the plan to remove the vROPs nodes from cluster and kept it in view of future data growth.