My Nikon to Canon EOS lens adapter is stuck. How do I remove it?

After recently receiving a Nikon lens adapter ring for my Canon EOS 600D, I decided to attach the adapter to a Nikon 18-55mm lens but I couldn't remove. I have tried moving the adapter's black lever in every single direction I could think of and I have tried twisting it off the lens but it still remains stuck. Suggestions, anyone?

Why would you even consider using a Nikkor lens on a Canon camera?

Many adapters are poorly made and really convert an auto-focus lens into a manual one.

You are going to have to take your camera and lens into a camera repair shop and have them remove the lens and adapter for you so you do NOT damage your 600D

My guess is you had a Nikon camera with 18-55 mm lens and you decided you NEEDED a Canon 600D. I'm curious why you did not just buy a nice Nikon D5100.

Here is how the two sensors compare, the 600D and D5100

http://94.23.12.156/index.php/en/Cameras/Compare-Camera-Sensors/Compare-sensors/(appareil1)/698%7C0/(brand)/Nikon/(appareil2)/692%7C0/(brand2)/Canon

These lab tests begs the question why you decided to change camera systems

Adapting Nikon lenses to a Canon camera is perfectly valid, I do it all the time with my 58mm f/1.2 Noct-NIKKOR that I bought used for parts on ebay and repaired. That's why I went with Canon -- the larger diameter mount and shorter registration distance lets me mount upwards of 27 different brands of lenses with the proper adapter. Heck, Canon actually supports more Nikon lenses than Nikon at the 600D price range if you include Non-Ai Nikkor.

Which adapter did you buy? Typically, the $10 chinese adapters on ebay are not built to strict tolerances, and some may fit a bit too loose or a bit too snug. What I find useful is to pull the lens release lever and move it ajar so that it holds open*, then use a Canon lens cap (for the back of the lens) and use that for leverage to twist. If that doesn't work, could you post some photos on your flickr and link to them? I'd need to see which design of adapter you're using to know what exactly is going wrong. Worst case scenario, you may find yourself with a Dremel in the near future -- I can give you some steps with that as well.

Also, unless you have an aperture-coupled adapter, which costs around $250, you're not going to be able to use your 18-55mm very easily. You need lenses that have a manual aperture ring (or again, buy the expensive adapter). Otherwise, to set your aperture to anything other than wide open, you will need a Nikon camera -- set the aperture on the Nikon camera, then mount the lens on the Canon with the adapter (the aperture will stay set at whatever you chose on the Nikon). For some extremely specialized lenses in a studio setting, this may be worth the trouble, but it seems like a bit of a hassle just for an 18-55mm.

*You can also fit a bit of paper under the release tab if you can't get it to stay open while you're twisting it.

Edit: Now that I re-read your question, I'm not sure whether you mean that the lens is stuck on the camera, or the lens adapter is just stuck on the lens. If the lens adapter is stuck on the camera, you may have a small situation -- it may be getting jammed on the AF/AE pins of the camera. That would not be good -- fixable in the right hands, but not good.