Hard Drive Clean Up
My 21" iMac is running so slowly I can't do anything. I noticed the other day that there were a bunch of download arrows on myCloud drive -- it appears it's trying to download to my Mac. I also noticed a quick message that I was running out of space on my iMac. I have no idea how to clean up my hard drive on this computer (I was schooled in Windows (i know!!) -- so until I'm able to figure it out, I'm sort of screwed in doing anything on this computer. Can anyone point me to where I go to delete a whole bunch of stuff off my hard drive? Thanks in advance.
iMac 21.5", macOS 10.14