1. ClickModify > Delete Duplicate Objects 
2. At the Select Objects prompt, use a selection method to select objects.
3. Press Enter.
4. Optional:
   • Specify a Tolerance value.

     Defines the value within which OVERKILL makes numeric comparisons for determining object duplication.

   • Select properties to ignore during object comparison.
   • Set additional options to optimize polyline segments, combine objects, or maintain associativity.
   • Click OK.

Try the following for unused objects.

1. At the Command prompt, enter purge.
2. To purge unreferenced linetypes, use one of the following methods:
   • To purge all unreferenced linetypes, select Linetypes.
   • To purge specific linetypes, double-click Linetypes to expand the tree view. Then select the linetypes to be purged.
3. You are prompted to confirm each item in the list. If you do not want to confirm each purge, clear the Confirm Each Item To Be Purged option.
4. Click Purge.