Format an external USB Drive

I installed Nextcloudpi on an Odroid-hc1 a few days ago and everything has gone great. I have a small snag though. I went to [ nc-format-USB ] to try to format the sata drive and got the following error:

ERROR: counted 2 devices. Please, only plug in the USB drive you want to format

The only other connected media on the device is the micro sd card. Am I suppose to unmount the sd card, and how do I go about doing this from the command line?


what is the output of lsblk -f?

Sorry for the delay, but I have been out of town.
This may not help as I have successfully set up (I think) my two drives on the odroid-hc2, one sata and one usb. but here is a pic of lsblk -f