Purge

WBLOCK is the cure!
Russ

Make sure those layers are not set to "Freeze in Current Viewport" in a paperspace viewport.

in the layer manager, you can try a right clik on the layer and delete. sometime it's working a écrit dans le message de news: snipped-for-privacy@f14g2000cwb.googlegroups.com...

That's a bit drastic. He will lose all views, viewport setups, UCSs, unused styles and blocks.
The problem is more likely much simpler to solve. Check that floating viewports do not have the offending layers frozen in them before you purge. If that doesn't work, look into your block definitions. Some may have had these layers "current" when they were made, so that even if there were no entities on these layers, they are defined in these blocks. For that matter see if there are blocks you can purge, they may contain the block definitions.
One more thing, if the layers came in with an XREF they cannot be purged in the host drawing.

You can install Express tools if you did not yet, and there you have Layer delete. That will work 100 %. You just have to draw one line with this layer you want delete, and than choose Layer delete and select this line. Anything in this layer will vanish.