Is this slander?

First thing you need to understand is that the forum is a private entity, and the admins and moderators are agents of that entity, acting on it's behalf. Being a private entity, they are not bound to the First Amendment (assuming you and the site are in the US). The First Amendment only pertains to the government. The first few words tell you that - "Congress shall make no law..." (it is extended to include state and local governments by the 14th Amendment - "No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States").

With that being said, it is at their (the admins and moderators) discretion as to what can and cannot be posted to the forum. Whether or not your post, or your question of why you cannot post it, is slander or not is very difficult to answer without seeing the original post and your follow up post. It's all in the wording of the post as to if it is slander or not (actually would be libel since it's written - slander deals with spoken comments, but otherwise the two are the same meaning, and many people confuse them).

So if you would be so kind as to post word for word what your are referencing, that would go a long way in answering your question.

I suspect that the person who made the comment doesn't really know what slander is, since it doesn't sound as though you committed slander (which is spoken, not written, anyway).

But it doesn't matter. As you've been told by other posters, online sites are mostly private entities, and the owners/moderators have the discretion to decide what can or cannot be posted and what can be removed.

Maybe your first post was slander and they figured you would slander them as well. Slander is making verbal false statements about someone. Libel is in writing. So technically, it would be libel. It's a private board, so they can take down what they want. You should have contacted a moderator privately to ask what was going on rather than publicly. By doing it publicly with the screenshot, you are implying they are incompetent, or other negatives. So it could be construed as libelous.

The forum is protecting their brand by removing your post - they apparently think it puts them in a bad light. It's legal to do - it's called moderation. I do it all the time on my blogs and forums.

This is the definition of slander:

n. oral defamation, in which someone tells one or more persons an untruth about another, which untruth will harm the reputation of the person defamed.

They also don't owe you an explanation as to why they removed the post, though if you read the terms of service and rules, it should give you a good idea.

No, that is not slander. Their website, their rules. He can take down anything he wants.

By the way, slander is verbal. Written defamation is called libel.

No. Slander is spoken, NOT written. You might have defamed them. Regardless, you don't own the website. The website owner has the right to remove any posting they want to. It would make no sense to leave it there and then sue you for defamation when all they had to do was resolve the problem by removing it.

Removing a post is not slander. As for your initial post...depends what you said.

You would actually have to post the exact wording for an answer. We can't go by the information given.....

No

But it's their forum and they have a set of rules

It is only if you didn't tell the truth.