One of our Tip Patrollers, Mitch Hirschklau, shares a tip on purge-resistant items in AutoCAD.

"On the subject of purging unwanted and seemingly unpurgeable layers (and Dimstyles, linetypes, textstyles, and other items), I have a low-tech trick which might help when all else fails. Sometimes the best way to purge an unwanted item is to purge something else instead. Rename is your friend in this process — with a little help from Change or Properties. Here is what you do:

1. Change the Properties of objects on a layer you always have (like 'A-GRID') so that they now reside on one of your unpurgeable layers.
2. Purge that now unused, typical layer out of your drawing.
3. Rename the unpurgeable layer to the name of the just-purged layer. (Don't forget to change the linetype, color, etc.) Your layer list is now reduced by one.

In general, this same technique works with linetypes, Dimstyles, and textstyles too. Mtext can sometimes get a little 'sticky' with respect to textstyles. And, you'll usually need to redefine some textstyles (and/or Dimstyles), as well as re-name them. In all honesty, this is more of a 'Now you see it, now you don't' kind of trick than a real fix. If the problem is unneeded items contained in a block, the next time you perform an Insert, they'll be back! Still, hiding stuff is sometimes quicker and easier than removing it."

Notes from Cadalyst Tip Patrol: AutoCAD files will develop issues like unpurgeable items from time to time. What happens is that AutoCAD thinks the unpurgeable layer has at least one object on it, even if you select all and delete everything. This can be caused by a zero-length line or empty text objects. The items exist, but since there is nothing in them, there's nothing actually there. In AutoCAD 2010, a Purge Zero Length Geometry and Empty Text Objects feature was added. Try that new feature first, and if it doesn't work, turn to this tip — it's a very creative way of getting around this problem.