Do you mean that you cannot delete the file name from the Most Recently Used file list? If so, then read this
Fill the MRU (Most Recently Used) list with bogus file names
http://www.pptfaq.com/FAQ00373.htm

 I can delete slides, but I cannot delete the presentation name out of power
 point, what do I do?

Judy,

if you want to delete your 'whole' presentation from your computers hard
disk....

Then

File  > Open > navigate to your presentation filename > click the filename >
press the Del key on your keyboard > confirm that you want to delete the
file and move it to the recycle bin

cheers
TAJ Simmons
Microsoft Powerpoint MVP

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