Keep it simple - the meeting is finished. my meeting has finished. I have finished the meeting. I am through with.....this is used, sometimes, to express anger and frustration. "I am through with this pandemic / lockdown. I want out!"

Paul's examples are perfect but as a Canadian I would use "I am through with my meeting" after the meeting, on the phone, to someone who was not in the meeting. Eg, "Hi Jeff, I am through with my meeting, let's meet for some lunch."