swlist -l patch \*.\*,c=patch 

lists all patches on the system

They can be in applied status (i.e. they can be rolled back), committed (can't be rolled back) or superseded (speaks for itself!).

To save space, patches can be committed. This removes copies of files and library objects prior to the patch from /var/adm/sw/save (This is why they can't be rolled back). Patches can be committed using:

swmodify -x patch_commit=true PHxx_xxxx \*

It is always advisible to backup /var/adm/sw/save first!

For more details see /usr/share/doc/patch_pgrm.txt on a HP-UX 11 server.