How do I remove a player from my plot? How I remove the permissions from a specific player?

At this time, there is no way to remove a player from your homestead.

You can, however, remove the permissions given to a player by interacting with the Homestead control panel. Once in the menu, select permissions, which will display a list of players who have been given permissions.

By selecting the player name in the list, you can remove its permissions.