Unload currently loaded packages from the current R session
flushSession(dontunload = switchrDontUnload())
NULL, called for its side-effect of unloading packages
Non-base packages to ignore (not detatch/unload)
Attached packages are detached (and unloaded) first. After this is done, loaded packages, such as those imported by (previously) attached packages, are unloaded.
Finally, after all packages have been unloaded, native libraries loaded by those packages are unloaded (on systems where this is supported).