It's alright to delete these files?

I have every client, and every one has some html files on the Data folder, they're AccountBilling, connection-help, Credits, eula, TechSupport, tos, etc.

I know that these files doesn't take too much space, still, i don't want files that i won't be using, so i don't have any other idea to delete them.

Also, on the MoP client, there are some enGB, enUS and ruRU folders, and in others folders there are other enGB folders, so i think that's the "core" language of the client? and what about the other two (enUS and ruRU), can i delete them?