From this article, is it really safe to do it like this without losing anything important especially using the Erase Tab? thanks for a reply..... Really delete filesKeeping drive space free helps boost Mac responsiveness. Files arent truly deleted when you delete. Traces of them continue to exist until the now "free" space they used to occupy is overwritten. To make the most of the space you've created on a hard drive (HDD) Mac by deleting things you don't need anymore, follow this tip: Empty Trash in Finder Launch Disk Utility Select your computer hard drive Select the Erase tab Now press Erase Free Space button You'll see a new dialog appear, (pictured). The sliding scale lets you choose between the Fastest and Most Secure options to write over unused space. Choose Fastest for a simple free space over write. Click Erase Free Space Now all your deleted items will truly disappear.