See the attached python script, kindledrm.py, which reports the status of an AZW ebook. Note that kindledrm is not touching the file's DRM, it just looks at a 2-byte integer in the header that indicates the presence of DRM.
Using a windows command for loop (see the readme in the .zip) I found the following DRM-free AZWs on my Kindle:
DRM-free Graphics on the Kindle-asin_B0018LILMO-type_EBOK-v_0.azw
DRM-free Pride and Prejudice in Extra Lar-asin_B0019HWY1Q-type_EBOK-v_0.azw
DRM-free A Canticle For Leibowitz-asin_B001IV5SES-type_EBOK-v_0.azw
DRM-free The Complete User s Guide to the-asin_B0011XW1E8-type_EBOK-v_0.azw
DRM-free Asimov s Science Fiction 01 01 2-asin_B001KC06OW-type_MAGZ-v_1.azw
DRM-free Homicide My Own-asin_B001G0MKVU-type_EBOK-v_0.azw
DRM-free Startide Rising-asin_B001PBF0MG-type_EBOK-v_0.azw
DRM-free The Solomon Scandals-asin_B001T4YANY-type_EBOK-v_0.azw
DRM-free White Witch Black Curse-asin_B001NLKRY4-type_EBSP-v_0.azw
Several of these are "Extra Large Print" ebooks that are no longer available. The others can be found by searching at Amazon for the ASIN which is in the file name (e.g. B0018LILMO). The script also finds DRM-free samples (White Witch is the only example here), which are typically labeled EBSP rather than EBOK. Most (all?) samples are DRM-free.