I can't speak for all the downvotes, but I was one of them for a reason that came up several times in the comments and was pointed out in the answers: there is such a clear disconnect between your quote and your examples that it didn't seem like you could possibly be asking your question in good faith.
The definition of freedom of speech you found states that speech is protected 'without censorship or restraint by the government', and you then list two examples you think violate this protection: one where a private company banned a political figure from posting on their website, and one where a private company stopped offering website hosting services to another private company.
Neither of your examples were related to restrictions by the government in any way, and restrictions by the government was a key part of the free speech definition you said those examples violated. This made it seem to me (and, judging by similar comments/answers, several other downvoters) that you were just trying to make a point or spread a view rather than to actually ask a question and get an answer.
However, it's clear that the substance of your question isn't inappropriate: your question has been marked as a duplicate of a several similar questions, and a few of those are highly upvoted and have many thorough answers. The only issue is the way you asked your question, since this seemed to cause many other user to perceive it as not a genuine question.
So, if you still are looking for answers to your question I think there are two directions you could go:
- keep the definition of free speech in your original question but find examples of the government restricting speech and ask about those
- keep the examples of private restrictions and find some definition/claim that those actions violate free speech in the US (or another country if you're interested)
Both of those options seem like they would be entirely on-topic (assuming they haven't already been asked on here), and would still get at the core of what you were asking while hopefully avoiding the sort of negative response that your original question got.