I own the "espectator" DOTA 2...

i heard some people got the same problem

And there is no option to erase that from my steam history, this sucks ._.

No solutions yet.
Also removing the game from your library list won't do a thing.

For anyone that really wants the game and for whatever reason can't find someone that has a copy to give you and you are striking out with the giveaways, you can buy this - Dota 2 Invite - but really, if you just reach out to people it's very likely you can pick up a free gift beta copy (just be sure to follow forum rules and don't publicly "beg" for keys). Hopefully the issue Ojcar encountered gets fixed because there are so many copies!