what i did was create a new Helper class file (Javascript Class), then added all the Colyseus functionalities and listeners and everything there. so I can store the room in a variable there like this.room which can be accessed from any other component on my whole application.

class ActivityRoom {
    constructor() {
        this.client = new Colyseus.Client(clientUrl);
    }

    connect = async (username, rating, photoUrl) => {
        this.name = username;
        this.rating = rating;
        this.photoUrl = photoUrl;
        try {
            const room = await this.client.joinById('AR1', {
                username,
                rating,
                photoUrl
            });
            this.room = room;
            this.sessionId = room.sessionId;
            this.Room_Listeners();
        } catch (error) {}
        console.error(error);
    }
};

leaveRoom() {
    this.room.leave();
}
}

then call the leaveRoom like ActivityRoom.leaveRoom from any other Component i want.