Delete all items in the list

[Clarendon]

Hi. This must be a simple command but I just can't find it in the
Phthon manual. How do I delete all items with a certain condition from
a list? For instance:

L=['a', 'b', 'c', 'a']

I want to delete all 'a's from the list.
But if L.remove('a') only deletes the first 'a'.

How do you delete all 'a's?
I would really appreciate your help.

Thanks.