I have erased and reformatted several times, but partition in Disk Utilities continues to be greyed out. I have even tried different Macs with Mojave. I have other external drives partitioned, and First Aid doesn't show anything wrong with the external drive. I am really at a loss.
Select the KESU USB 3.0 Media as you have highlighted in the screen shot. Click on Erase in the top tool bar. Select macOS Extended( Journaled) with a GUID Partition Map Scheme (not Master Boot Record) as your screenshot shows. Click on Erase at the lower left of the drop down box. When it is finished, the Partition button should be solid colored and no longer greyed out. Click on the Partition button and the partition drop down box should show Partition the drive as you wish.
Change the View dropdown menu in the toolbar to Show all Devices, then take another snap of EXTERNAL. You cannot partition the drive because you have formatted it which creates a new volume. It's that new volume that you can partition. If you did everything as default, then the new volume should be named, "Untitled." If you select that volume in the new View, then you can partition it.
I see this is already been answered, so disregard this.
Thank you for your response; I did try that but unfortunately the partition option is still greyed out. I'm wondering whether there might be a problem with the drive itself.
Thank you SO much. I could not figure out how to get to the Scheme option from reviewing other responses to this issue. Your answer solved my problem and I learned something new. Thanks again.
Unable to partition external hard drive on Mac using Mojave
