Hello Prasad,
You want to deactivate the warning message related to tax code for the parked documents.
in standard the messages controles are managed independently from document type or posting/parking criteria.
you will still get the warning message unless you desactivate the message, but then it will be desactivated for all document type, all process.
No user exit or FM is possible (may be check enhancement points to avoid message)
try maybe a substitution that will populate the tax code with a dummy one if no tax code exit, and apply only in parked document case, its better than tapping enter 1000 times
Regards
Tamim