What does it mean by "trolling" at Chess.com?

No. It's not trolling.

If you have turned someone down and they keep asking after you have asked them to stop, you can just block them or remove them from the club.

The reports are supposed to be for reporting abuse, not any minor annoyance. 

I don't know the particular circumstances of what you are talking about.  I guess you have to be the judge of whether or not you think their behavior would justify potentially having them banned from the site.

This not some minor annoyance this member is also sending messages to the club owner that he wants to become a SA or Admin. A club owner said me this.

Edit:

No one turned him down. he just wants the SA and Admin

When i report someone, i see an option called "trolling". What does it mean? Like if you play Bongcloud is that trolling?

Well fine. If you just want to be a troll, I shall treat you as such.

Sorry, are you telling the person who was complaining about repeatedly being asked to be a club admin, that they should report such things as racism?

That is not right.

If that was a joke, it was not funny.

Well why don't you or the club's owner do that? And just ask him to stop.

.

https://www.psychologytoday.com/us/blog/writing-integrity/202008/why-do-people-troll-online

Trolling is multi-causal. This means that it isn’t caused by any one reason, but rather by many reasons that can add up and interact with each other in a perfect storm to produce trolling. The most helpful way to think about these causes is to divide them into two broad categories: reasons outside of a person (i.e., environmental factors) and reasons inside of a person (i.e., individual factors).

Environmental factors that contribute to trolling:

• The online disinhibition effect: This phenomenon describes an illusion of invincibility and invisibility. A person is more likely to troll from behind a screen than face-to-face due to a false sense of security. Metaphorically, the online environment can produce a sort of mental veil that seems to open a release valve into some of the darker corners of human nature—not unlike the “liquid courage” and disinhibition that alcohol can provide. Unsurprisingly, combining the online disinhibition effect with alcohol use can be a recipe for disaster.
• Anonymity: If a person engages anonymously online, then it’s like the online disinhibition effect has just taken steroids. It is easier to troll with the illusion of no accountability and no connection to one’s life off-line.
• Tribalism: The power of the group can add more fuel to the fire. Like a pack of wolves, humans are social creatures and have an innate desire to be part of a group. When many members of a group are trolling a target, a sense of belonging can be achieved by conforming to the group’s behavior.

Individual factors that contribute to trolling:

• Personality: There are many ways of understanding personality. In essence, personality traits are deeply ingrained patterns of thinking and behaving. One way to understand one particular aspect of personality is to focus on some of the darker sides of human nature, which researchers have called the dark tetrad: sadism, psychopathy, narcissism, and Machiavellianism. The dark tetrad has been found to be associated with trolling. Within the dark tetrad, sadism has been found to be the strongest predictor of trolling, which describes the tendency to derive pleasure or enjoyment from being cruel or demeaning to others. It is important to recognize that sadism in this sense occurs on a spectrum—people can have more or less sadistic tendencies.
• Ideologically possessed beliefs: Some people are married to their beliefs and don't believe in divorce. In other words, some people can rigidly over-identify with particular beliefs (e.g., about health, gender, racism, politics, etc.) to the extent that they might engage in trolling behavior when those beliefs are threatened. People don’t like it when their worldviews are poked and prodded because it can be very upsetting when someone is told that the way in which they understand the world is wrong. It can also feel personal and can result in lashing out for protection. Research has shown that people perceive trolling as more deserved and justified when they perceive that the target has committed an offense.
• Conditioning: Not everyone finds demeaning people to be rewarding and reinforcing. But this is the experience of people with stronger sadistic tendencies. One framework to help understand trolling is what psychologists call operant and classical conditioning. Operant conditioning is the study of rewards and punishment to influence behavior. For some, this might dredge up images of rats or pigeons dancing for food pebbles. Basically, trolling behavior can feel rewarding in two ways: the pleasure experienced from getting a rise out of a target (positive reinforcement) and in some cases, the pleasure experienced by avoiding or distracting from aspects of life that are uncomfortable (negative reinforcement). Like a slot machine, randomly responding to trolling just strengthens the motivation for it to continue. Simultaneously, there are classical conditioning processes going on—reminiscent of a dog that salivates when you open the cupboard because they know they’re about to eat. A dog salivates because they’ve learned that the cupboard represents food. In the same way, people with sadistic tendencies that engage in trolling may salivate, so to speak, when they learn that their target represents the pleasure that they’ll experience when they troll.

Trolls are people who leave intentionally provocative or offensive messages on the internet in order to get attention, cause trouble or upset someone.

Source:Google

Its a source, and can be a good source.  The problem is that most people just click on one link and go: "Yep...that's the truth."

Exactly.  Google is a source to get the information. 

We did tell him to stop but he still continues

We did tell him to stop but he still continues

Google is not a source.