If stripping the damper you will need to depressurise the nitrogen gas charge. There is probably a valve, but if not the damper case can be drilled and later tapped to take a filling valve.
compress spring
take all preload off
theres a small grub screw just where the preload flexible pipe connects to the head preload unit on the shock body undo this
push the whole head assembly down revealing a large spring ring round the head of the shock body remove this
lift off preloaded assembly
remove spring
reassemble in reverse ensure the large spring ring sits back into its groove int he shock header