SAS Software Depot is a directory structure from which you install SAS software. You download your order(s) to it using the SAS Download Manager. It is safe to delete the depot after you're done installing SAS software. There are no runtime requirements for the depot by SAS products, but if you intend to download future orders, you can end up saving space by leaving the depot around, and downloading the new orders into it. The depot maintains a single copy of any given software deliverable, so if your orders have overlap in deliverable content, only one copy is maintained.
SASHome is the installation directory which maintains all the binaries used by SAS at runtime. This is obviously necessary for any SAS products you continue to run. If you uninstall all SAS software from your system, you can safely delete this folder as well (there are times when the uninstall routine is unable to delete all files when it's executing). However, take note that different versions of SAS products can be installed into the same SASHome directory. As such, unless you have uninstalled *all* versions of all SAS products on your system, you could be undercutting software you still intend to run by deleting the entire SASHome directory.