I often delete the backup partitions on computers when I think the space can be better used as part of the main C drive. This is especially useful when a client has an SSD, which still are mostly smaller than the older sata drives. Plus I install disk backup software on client's computers. This is better than a factory restore because you restore the files and programs too.
I go into disk management, delete the recovery partition and then expand the C drive. The recovery partitions usually show themselves as primary partitions. Right now I'm looking at a drive in a Lenovo desktop computer that's showing itself as an "OEM partition", rather than a primary partition. It's not the active partition. Can this OEM partition be deleted safely.