OEMDRV is Default OS Development Drive created by lifecycle controller of Dell Servers and contains the drivers used while installing the server.
In our case OEMDRV was E: and we wanted to use that drive letter to install some of our softwares, we were also unable change the drive letter or eject/delete it using disk management though the drive gets automatically removed after 18 hours and we did not wanted to wait that long in order to complete the server setup at the earliest..
But there is another way to force remove the volume, simply enter and exit the lifecycle controller during boot.
Restart the server and Press F10 to enter lifecycle controller during the time of boot and simply exit it (no need to change any settings).
This will remove the OEMDRV partition.