Yesterday evening, I was in an English voice chatting room to practice my listening.

A person named Harry was also there.There was this guy there named Harry.

Your sentence grammatically is fine, but native speakers would phrase it a little differently. My sentence is a little more colloquial but generally people would say something like "There was this person/guy" and then say something about his name is Harry.

He was very annoying .

In my opinion, he is a bad person with low quality.

You don't need to say "low quality" because you already say he is a bad person. Also generally we don't describe people as high/low quality.

I cannot censureor him because my spoken English is not good.

From my point of view, anIn my opinion, everyone in an English voice chatting room should follow the room rules and be a nice person with nice behavior.

"In my opinion" is a more natural way of saying "from my point of view." Anyone is technically okay here, but people will usually use everyone in this case because you are talking about how all people should follow the rules. Again, you don't really need to say "nice person with nice behavior", just "nice person" is fine. Generally we don't say "nice behavior" but instead "good behavior."

Remember that you comego there to practice your English, not to cause trouble.

In most cases we will say "go there" and "come here". "Go here" is used occasionally when giving directions. "Come there" is almost never used. I believe we do the same in Chinese. I hear "去那边，来这边" way more than "去这边，来那边." In this case, both "go there" and "come here" are acceptable because your location is vague.

Besides,And not to speak Chinese all the time.

I would just add this to the previous sentence. "not to speak Chinese all the time" is not a full sentence so your sentence is grammatically incorrect. If you want it to be a separate sentence, you could say something like "You should not be speaking Chinese all the time". Besides as a conjunction doesn't really make sense here because you are adding on to your previous sentence. So I would use something like "also" or "plus".

Yesterday evening, I was in an English voice chatting room to practice my listening.

He interrupts others, says bad wordsuses profanity, and causes trouble.

Your sentence is grammatically correct. Also, the phrase "bad words" is accurate enough. However, this English idiom is used mostly by and for young children. When a child uses profanity they have heard from someone else, adults correct them by saying, "That's a bad word." Teenagers and adults usually prefer to call such words swearwords, dirty language, foul language, vulgar language, or profanity. If one adult says to another adult, "That is a bad word," those who hear will think that the speaker is intentionally scolding the profanity-user as if they were a young child. Certainly, that word choice is effective in some circumstances, but in this context, it does not seem to be helpful in expressing your point.

In my opinion, he is a bad person with low quality.

This sentence is grammatically correct. I just want to suggest some more descriptive English terms for this guy: worthless, sleazy, a public nuisance, a creep, a scoundrel, a lowlife, a good-for-nothing and a loudmouth. I think the best word might be "troll."

Remember that you coame there to practice your English, not to cause trouble. and certainly not to speak Chinese the whole time.

"Not to speak Chinese all the time" is not a complete sentence. It should be joined to the previous sentence with a conjunction.

Besides, not to speak Chinese all the time.

My intuition tells me that "besides" is not the proper word to convey your meaning in this sentence. I have searched several online dictionaries to help me explain why not, but I cannot find the answer. Still, it is my opinion that you should replace besides with certainly and join the two clauses with a conjunction. Perhaps someone else might have a better understanding than I do of the uses of besides.