How to remove closed notifications from work list

 Hi, 

I am trying to remove a closed iRecruitment notification from my notification work list.  

I have tried running the job 'Purge Obsolete Workflow Runtime Data '  I entered both the type and item key of the specific notification in the parameters.  However, his was unsuccessful. 

Is there anything else that I should be doing? 

I have had a look at numerous notes and documents on MOS and haven't found anything specific to what I am trying achieve, except the note/doc on the above job.

I would really appreciate some help on this please! 

Kind regards

Sof