Delete Mesh by Material Is it possible to delete a part of a mesh by its material? And how?
For example, I have a tree that I want to add snow to. But it comes with cards for foliage. This will not work with 3DM Snow or Real Snow with any desired results.

Though on a side note, if you know how 3DM/Real Snow could work with cards and look pleasing I'd be interested too but from my logic I don't think it would ever look nice.
To delete a part of a mesh by its material, you have at least two options.
For both to work you'll have to first enter edit mode (press Tab).
First option is to select by material. Here you can see where to find this command:

After running this command, you can press Del key, and select delete faces from popup menu.
Another option is to use separate by material. You can find it here (or press P in edit mode):

When you have separated part of your mesh into another object, you can do whatever you want to it, like delete it.