Can't Delete Calendars
Assuming you use iCal (not specified in your question), then the Subscribed calender should appear under subscriptions.

UN-checking them will stop showing them.

If you trying to completely remove them then Right Click on the calender and Delete in the Pop up.





If above fails lets do the "brutal" method:


First make an iCal backup:  Click on each calendar on the left hand side of iCal one at a time highlighting it's name and then going to File Export > Export and saving the resulting calendar file to a logical location for safekeeping.
Go to iCal > Quit iCal
Remove the following to the trash and restart your computer:



  Home > Library > Caches > com.apple.ical
  
  Home > Library > Calendars > Calendar Cache, Cache, Cache 1, 2, 3,
  etc. (Do not remove Sync Cache or Theme Cache if present)


Launch iCal and test.

If the issue still persists at this point:

Remove the following to the trash and restart your computer:


  Home > Library > Caches > com.apple.ical
  
  Home > Library > Calendars > Calendar Cache, Cache, Cache 1, 2, 3,
  etc. (Do not remove Sync Cache or Theme Cache if present)
  
  Home > Library > Preferences > com.apple.ical (There may be more than
  one of these. Remove them all.)


---NOTE: Removing these files may remove any shared (CalDAV) calendars you may have access to. You will have to re-add those calendars to iCal > Preferences > Accounts.