When working throughout your Photoshop composition, whether it’s a website, print ad, design for fun and so on, we may tend to lock layers as we go. Some of our site files can be over 1000+ layers so going back and finding those locked layers can become a nightmare.
When I get requests from developers for an update to one section I typically save that specific page as a new PSD instead of saving to the “master file” which would contain all of the pages.
If you need to remove all of the layers (which some may be hidden and locked) the easiest thing you can do is the following:
1. Select all the layers you don’t need using shift and/or control
2. Merge your selected layers (Ctrl + E)