Unused textures and meterials make file way too big

Support Basics & Interface
1

I like to have separate Blend files for each animation I do of my spaceship in a different surrounding. They are not linked together, but I have a file for each setting. Putting them all in one file would be too big. I do not use all the materials/textures/objects/meshes in each, though; I only use what I need. Unfortunately, the info is still there, making the Blend file huge, even if the model has a single, untextured plane.

So:

How do I delete data sets from the file, such that no trace is left of it is left? This would trim the Blend file by a few megs, at the least.

Thanks!

2

Use shift-F4 to go to a list of your materials. The list of your objects will likelly appear first. So. . .
Go out of “Object” list up a level and then to “Materials”.
You’ll see your list of same. If there are any with an “F” that means they’ve been assigned a fake user. Hit “f” and the “f’s” on the list will change to zeros. Then save, close and reopen. The materials with zeroes will now be gone.