The plaque was on a HBC building, it is their's to remove it if they choose. 

The issue I have is how people in the US have determined they don't like what a statue stands for and are pulling them down. Rightly so, I also have read they are being arrested.

This is nothing more than vandalism. No different then someone spray painting a wall etc.
Don't like the statue, there is a lawful process to follow to have it removed.

The people pulling them down have appointed themselves judge/jury and executioner.