Make clean gets ready for another possible compilation. This is useful if you are not building the same kernel several times due to edits. It will delete all the object files (and object libraries). The result is as if you had done a make menuconfig, but not built the kernel yet.
Make depclean deletes configuration files generated as part of the make menuconfig step as well.
A running kernel does not depend on anything from the source directory. Usually, the kernel is configured and compiled in a user directory - only the install (which writes into /boot) steps require root.
Once the install is complete it is possible to delete the entire source kit.
Last edited by jpollard; 07-11-2015 at 07:09 AM.