Here are the timetables:
Time Limit on Editing a Thread Title: 10 minutes
Time Limit on Adding a Poll to a Thread: 15 minutes
Time Limit on Editing or Deleting Posts: 48 hours
After these time limits only moderators will be able edit or delete the things listed above and only mods can delete an entire thread...and that's only if its your thread and you have a very good reason. ;)