Can't Unmount Drive - Help!

[legaleye3000]

I have two partitions. I'm trying to erase 1 partition in disk utility. When I click the "-" button to remove the partition, it starts but then returns an error message saying it can't unmount the drive. Please help. Thank you.

 

[simsaladimbamba]

What is on that partition?
Can you make a screenshot and attach it to your next post?

 

[heisenberg123]

I have two partitions. I'm trying to erase 1 partition in disk utility. When I click the "-" button to remove the partition, it starts but then returns an error message saying it can't unmount the drive. Please help. Thank you.

Is anything from that partition in use maybe in the background?