Remove or backout patches in Solaris
Contributed by qmchenry 
Tagged: Solaris system administration By default, the files replaced by the application of a patch in Solaris are preserved to enable removal of the patch and restoration of the system to its pre-patched state.
To remove a typical patch, such as 116012-01, run this command as superuser:
patchrm 116012-01
If you specified a non-default backout directory during the patchadd process, you must specify that during the patch removal. If the backout directory was /var/tmp/patch/backout, then the removal command would be:
patchrm -B /var/tmp/patch/backout 116012-01
You must specify the fully qualified (absolute) path to the backout directory.
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james said on December 16, 2008
If you are stuck in a non-bootable state and have to mount / to /a, then you’d have to use:
patchrm -R /a 116012-01