Old animation datablocks

I’m currently working on the Allosaurus animation and I’ve a curiosity about Animation datablocks; if I add keys to the bones, in the “add datablock” button of the animation window are present all the old datablocks of animations I did time ago. I tried to delete them, saving, closing and reopening the file, but the old datablocks are always there.
This is not a problem (but maybe they increase the file size), anyway is there anyone who knows how to definitely delete them?
Thanks in advance

Env

I believe Carl explains how to do this quite well in the BlenderChar forum. Here’s the link:

https://blenderartists.org/forum/viewtopic.php?t=4006

Thank you very much for the link!

Env